Pulitzer Prize-winning film critic Roger Ebert has lost his battle with cancer.

The writer, who marked 46 years with the Chicago Sun-Times on Wednesday, died Thursday, the paper has reported. Ebert was 70.

Just yesterday, he revealed in a blog post a return of the cancer that cost him the ability to speak.

He said he would cut back on the number of reviews he wrote and pass the torch to other reviewers. But he was full of plans to continue his film festival, relaunch his blog and return to television with his At the Movies program.

roger-ebert-300--03314912

Roger Ebert lost his voice to cancer in 2007. (Associated Press)

He had written for the Chicago Sun-Times since 1967, but was recognized across the U.S. for his thumbs-up/thumbs-down reviews of movies, developed for TV with fellow critic Gene Siskel. Siskel died of complications from an operation in 1999.

Ebert was diagnosed with papillary thyroid cancer in 2002 and then cancer of the salivary gland in 2003. Despite surgery and radiation treatment, the cancer spread to his jaw, and a part of it had to be removed in 2006.

He continued the fight against cancer, revealing in 2007 that he could no longer speak. He stopped appearances on TV, but kept up his written film criticism, building his brand on the internet, developing a Twitter following as well as maintaining a website dedicated to film.

"My blog became my voice, my outlet, my 'social media' in a way I couldn't have dreamed of," Ebert wrote in his memoir. "Most people choose to write a blog. I needed to."

Ebert was the first film critic to win a Pulitzer Prize for his work in 1975 and one of only three to achieve the honour. He also was the first to get a star on the Hollywood Walk of Fame.

His reviews were syndicated in more than 200 U.S. newspapers.

In Ottawa, Prime Minister Stephen Harper tweeted he was "Sad to hear that Roger Ebert has passed away. Movies are a big part of my life and Roger was a big part of movie life."

The Toronto International Film Festival mourned Ebert in a release, saying: "More than a friend, Roger was family."

"He knew us from our humble beginnings, stuck by us and helped us grow, as only family can do. It is no exaggeration to say that Roger, through his championing, had a large hand in making us who we are today on the world stage. He was a pioneer, a true lover of film. His passing is a huge loss for cinema. He inspired us and will continue to inspire generations.

"We are taking this opportunity to remember and celebrate our beloved friend, Roger Ebert. Our hearts go out to [his wife] Chaz and to their family and friends."

Ebert's annual list of top 10 movies was hotly anticipated. He chose the Canadian film Juno to top his 2007 list and Sarah Polley's Away from Her was No. 6. For 2012, he picked Argo, Life of Pi and Lincoln, but also indie films such as Beasts of the Southern Wild.

"My loyalties are to my enthusiasms," he told Interview in 2001. "If  I really love a movie, I want to share that enthusiasm, and my unhappiest days are with movies I don't feel strongly about. It's very easy to write negative reviews and positive reviews, but it's very hard to write about movies that are in that gray area."

'If a movie is really working, you forget for two hours your Social Security number and where your car is parked.You are having a vicarious experience'— Roger Ebert

Ebert's movie reviews featured a star system, with four stars the best rating. His approach to film was populist —and he said he reviewed a film for what he felt would be its prospective audience.

"If a movie is really working, you forget for two hours your Social Security number and where your car is parked," he once said. "You are having a vicarious experience. You are identifying, in one way or another, with the people on the screen."

He wrote 15 books about movies and worked continuously on his list of Great Movies, his favourites from throughout movie history, which is available on his website.

Citizen Kane was a favourite

One of his favourites was Citizen Kane.

"You can have a movie with hardly any cuts, or very few cuts, that is fascinating, you can't take your eyes away from it … Look at some of the long takes in Citizen Kane," he said.

But his greatest influence probably was through his television reviews, initially with Gene Siskel of the Chicago Tribune and later with fellow Sun-Times columnist Richard Roeper.

Siskel & Ebert at the Movies, with its thumbs-up, thumbs-down approach to reviewing, ran on TV for 23 years. Chicago even boasts a Siskel & Ebert Way. After Siskel died in 1999, Ebert tried out a series of co-hosts and decided on Roeper, renaming the show Ebert & Roeper at the Movies in 2000.

He began a film festival, Ebertfest, at his alma mater the University of Illinois in 1992 and every year chose what he considered to be overlooked movie gems for the program.

Critical of Hollywood system

Ebert was critical of the Hollywood system, which he said paid little attention to what people want to see or to providing a range of choices. However, his embrace of indie films helped launch many of them to national attention.

"The movies that are made more thoughtfully, or made with more ambition, often just get drowned out by the noise," he said.

Roger Joseph Ebert was born in Urbana, Ill., on June 18, 1942 and studied at the University of Illinois at Urbana-Champaign.

In high school, he wrote sports stories for the local paper and edited the high school newspaper. He was later editor of the campus newspaper in university.

He did graduate study on a scholarship at University of Cape Town and went back to Chicago to work on his doctorate. There he became a feature writer for the Chicago Sun-Times and, in 1967, he was offered the position of film critic.

He and Siskel first went on air in 1976 on the local PBS affiliate. The show was picked up nationally in 1978. It moved into syndication in 1982.

He and later co-host Roeper were usually part of an ABC pre-awards show for the annual Academy Awards, and for some years they did red carpet interviews.

Nevertheless, he had very little patience with celebrity culture.

"I am utterly bored by celebrity interviews," he once said. "Most celebrities are devoid of interest."

Ebert dabbled in writing for film, doing the screenplay for the poorly received Beyond the Valley of the Dolls, based on a story he co-wrote with director Russ Meyer. He also wrote the screenplay for the 1976 movie Up!

Ebert frequently appeared on Howard Stern's radio show, where the host often asked him to defend his movie reviews.

He was frequently sharpest and funniest in his bad reviews of film.

"It's so witless, in fact, that when we do discover the secret, we want to rewind the film so we don't know the secret anymore," Ebert wrote of The Village, a 2004 M. Night Shyamalan horror film.

"And then keep on rewinding, and rewinding, until we're back at the beginning, and can get up from our seats and walk backward out of the theatre and go down the up escalator and watch the money spring from the cash register into our pockets."

Ebert was known for his distaste for films that feature violence in support of authority and for teen slasher films. He also quarreled frequently with the U.S. rating system for movies.

In the 1970s, Ebert began working for the University of Chicago as a guest lecturer, teaching a night class on film.

Ebert married trial attorney Chaz Hammelsmith in 1992 and had a stepdaughter, a stepson, and four stepgrandchildren.