Swedish author Henning Mankell, pictured here in February, is one of four Swedes on the aid ships who were released by Israel on Tuesday. (Mandel Ngan/AFP/Getty Images)

Bestselling Swedish crime writer Henning Mankell is on his way home after being held in Israel for participating in the Gaza-bound aid flotilla that was attacked by Israeli commandos.

At least nine people died after the commandos stormed the lead vessel in the six-ship flotilla on Monday, sparking a storm of protests and condemnation around the world.

The ships were trying to break the three-year Israeli blockade of Gaza and deliver about 10,000 tonnes of food, medicine and other supplies to the Palestinian territory.

Activists and diplomats from many countries, including Turkey, Canada and Germany, were part of the convoy.

They were taken into custody by Israeli authorities and given the option of immediate deportation or detainment at a prison facility in Beersheba and a trial in Israeli courts.

Swedish newspaper Expressen reported Tuesday morning that the 62-year-old writer — author of the famous Kurt Wallander series of books and most recently, The Man From Beijing — was already on a plane headed back to Stockholm.

"We are worried about our friends who are still in jail," the author told the newspaper, which also published a photo of him on the plane.

The Swedish foreign ministry would only confirm that four Swedes who had been on the ships were on their way home from Israel and another six remained in prison.

"I am so happy that he is on his way home now," Mankell's son, Jon, told Expressen. "It's good to see a picture of him, too. Now, I'm just waiting to be able to talk to him myself."

There had been confusion about Mankell's health. Late on Monday, a Norwegian politician told a crowd of protesters in Oslo that he had heard the writer had been shot during the attack.

The Swedish Foreign Ministry quickly quelled that rumour by confirming Mankell was unhurt.

About 480 other activists are still detained in Israel.