Ukraine's new president on Saturday called for dialogue with the country's east, gripped by a violent separatist insurgency, and for armed groups to lay down their weapons but said he won't talk with rebels he called "gangsters and killers."

Petro Poroshenko's inaugural address after taking the oath of office in parliament gave little sign of a quick resolution to the conflict in the east, which Ukrainian officials say has left more than 200 people dead.

He also took a firm line on Russia's annexation of Crimea this spring, insisting that the Black Sea peninsula "was, is and will be Ukrainian." He gave no indication of how Ukraine could regain control of Crimea, which Russian President Vladimir Putin has said was allotted to Ukraine unjustly under Soviet leader Nikita Khrushchev.

Hours after the speech, Putin ordered security tightened along Russia's border with Ukraine to prevent illegal crossings, Russian news agencies said. Ukraine claims that many of the insurgents in the east have come from Russia; Poroshenko on Saturday said he would offer a corridor for safe passage of "Russian militants" out of the country.

Rebel leaders in the east dismissed Poroshenko's speech.

Denis Pushilin, a top figure in the self-declared Donetsk People's Republic, said "At the moment it's impossible for him to come (to Donetsk for talks). Perhaps with security, a company so people won't tear him to pieces."

Poroshenko offered amnesty to rebels who "don't have blood on their hands." But "I don't believe it," said Valery Bolotov, the insurgent leader in the Luhansk region. Rebels in both Luhansk and Donetsk have declared their regions independent.

The new president promised "I will bring you peace," but did not indicate whether Ukrainian forces would scale back their offensives against the insurgency, which Ukraine says is fomented by Russia.

'Sound reassuring'

Russia has insisted on Ukraine ending its military operation in the east. Ambassador Mikhail Zurabov, representing Moscow, at the inauguration, said Poroshenko's statements "sound reassuring," but "for us the principal thing is to stop the military operation," adding that the insurgents should also stop fighting in order to bolster the delivery of humanitarian aid, RIA Novosti reported.

As president, the 48-year-old Poroshenko is commander-in-chief of the military and appoints the defence and foreign ministers. The prime minister is appointed by the parliament.

'I am calling on everyone who has taken arms in their hands — please lay down your arms'- Petro Poroshenko

Poroshenko, often called "The Chocolate King" because of the fortune he made as a confectionery tycoon, was elected May 25. He replaces Oleksandr Turchynov, who served as interim president after Russia-friendly president Viktor Yanukovych fled the country in February after months of street protests against him.

The fall of Yanukovych aggravated long-brewing tensions in eastern and southern Ukraine, whose majority native Russian speakers denounced the new government as a nationalist putsch that aimed to suppress them.

Within a month, the Black Sea peninsula of Crimea was annexed by Russia after a secession referendum and an armed insurgency arose in the eastern provinces of Donetsk and Luhansk.

In his inaugural address, attended by dignitaries including U.S. Vice-President Joe Biden, Sen. John McCain and Democratic Rep. Marcy Kaptur, Poroshenko promised amnesty "for those who do not have blood on their hands" and called for dialogue with "peaceful citizens" in the east.

"I am calling on everyone who has taken arms in their hands — please lay down your arms," he said, according to an interpreter. He also called for early regional elections in the east and promised to push for new powers to be allotted to regional governments, but he rejected calls for federalization of Ukraine, which Moscow has advocated.

Early elections

Biden later met with Poroshenko and said "there is a window for peace and you know as well as anyone that it will not stay open indefinitely ... America is with you."

Biden then met up with Canadian Prime Minister Stephen Harper. According to the PMO, their discussion focused on the situation in Ukraine, re-affirming the need for Russia to recognize the result of elections in Ukraine and agreeing intensify sanctions on Russia if events require it.

Poroshenko also said he would seek early parliamentary elections because "the current composition of the parliament is not consistent with the aspirations of the nation." The current parliament, elected in 2012 with a large contingent from Yanukovych's former party, is to stay in place until 2017.

Harper Europe 20140607

Newly sworn-in Ukranian President Peter Poroshenko met with Canada's Prime Minister Stephen Harper after the inauguration. (Adrian Wyld/Canadian Press)

Poroshenko insisted that Ukrainian would remain the sole state language of the country, but promised "new opportunities for the Russian language," without giving specifics.

He assumed power a day after meeting Putin at D-Day commemoration ceremonies in France.

Putin has denied allegations by Kyiv and the West that Russia has fomented the rebellion in the east, and he insisted Friday that Poroshenko needs to speak directly to representatives from the east.

After the low-key inauguration ceremony, which included a choir in traditional national costume singing the national anthem, Poroshenko went to the square outside the landmark Sophia Cathedral for a ceremonial troop inspection.

Poroshenko, Harper meet

Proshenko held several meetings afterwards with foreign dignitaries, including Harper.

"I am here on behalf of the government of Canada to express our solidarity with the government of Ukraine as you stand up for your unity your liberty and your territorial integrity," said Harper in a statement.

 Poroshenko‎ told Harper he wanted to thank Canada "for strongly supporting Ukraine."

"We can count on you as our closest friends," Poroshenko said. "And that's why I think it's important that you are the first official head of [a foreign] delegation with whom I have met as president. I think that's important."

With files from CBC News