Ukrainian military pilot Nadiya Savchenko has arrived home in Kiev after nearly two years in a Russian jail, as part of a prisoner swap in which two Russians held in Ukraine were returned to Moscow.

Key points: Kremlin says Savchenko was pardoned by Vladimir Putin

Kremlin says Savchenko was pardoned by Vladimir Putin Savchenko is widely seen as a symbol of resistance against Russia

Savchenko is widely seen as a symbol of resistance against Russia The two Russians are alleged to be special forces soldiers

Handing over Ms Savchenko, whose release had been demanded by Western governments and who has become a national hero in Ukraine, is likely to ease tensions between Moscow and the West a few weeks before the European Union decides whether to extend sanctions against Russia.

Ms Savchenko, 35, barefoot, and wearing a T-shirt depicting the Ukrainian coat of arms, emerged from the terminal at Kiev's Boryspil International Airport to cries of "hero" from a crowd of supporters, among them her sister and mother.

"I can't revive the dead, but I am always ready to lay down my life on the battlefield for Ukraine," a defiant Ms Savchenko said after touching down.

"And I will do everything possible for every person in captivity to be freed."

Following Ms Savchenko's return, President Petro Poroshenko vowed Ukraine would take back the annexed peninsula of Crimea and rebel-held territory in the east of the country from Russia.

"Just as we brought back Nadiya, we will bring back Donbass and Crimea under Ukraine's control," Mr Poroshenko said as he awarded Ms Savchenko with a Hero of Ukraine order, his country's highest honour.

In Moscow, Kremlin spokesman Dmitry Peskov said Ms Savchenko — who while in Russian jail was elected a member of the Ukrainian parliament — was granted a pardon by Russian President Vladimir Putin to allow her to leave jail and return home.

President Petro Poroshenko awarded Ms Savchenko with a Hero of Ukraine order. ( AFP: Genya Savilov )

Mr Peskov also said the two Russians, Alexander Alexandrov and Yevgeny Yerofeyev, were now back in Russia, having landed at Moscow's Vnukovo airport on a special flight from Kiev.

Ukraine accused them of being Russian special forces officers fighting in eastern Ukraine, though Moscow has never acknowledged the two were following its orders.

Ms Savchenko, a military pilot, volunteered to fight with a ground unit against pro-Moscow separatists who rose up against Kiev's rule in eastern Ukraine.

She was captured and put on trial in southern Russia, charged with complicity in the deaths of Russian journalists who were killed by artillery while covering the conflict.

Ms Savchenko was also accused of acting as a spotter, calling down the fire that killed the journalists, but denied the accusation.

A Russian court in March sentenced her to 22 years in jail.

Symbol of resistance in Ukraine-Russia conflict

She is widely seen in Ukraine as a symbol of resistance against Russia, a perception bolstered by her defiant behaviour in court during her trial.

At one point, she interrupted the judge reading out his verdict by standing on a bench and singing the Ukrainian anthem at the top of her voice.

Nadiya Savchenko shows her middle finger to the court during her trial. ( AFP: Yury Maltsev )

Mr Yerofeyev and Mr Alexandrov both said in interviews last year they were Russian special forces soldiers who were captured while carrying out a secret operation in eastern Ukraine.

Mr Alexandrov's mother, Zinaida, said on Wednesday: "I'm glad, I'm very happy. I hope that everything will be okay for him, I really want to see him."

Russia's relations with its neighbour Ukraine have been toxic since an uprising in 2014 forced out the Moscow-backed Ukrainian leader Viktor Yanukovich and installed a pro-Western administration. Russia then annexed Ukraine's Crimea Peninsula.

Moscow said it was protecting the local Russian-speaking population from persecution by the new authorities in Kiev, but Western governments called it an illegal land-grab and imposed sanctions on Moscow.

Soon after, pro-Moscow separatists began an armed separatist rebellion in the Donbass region of eastern Ukraine, an area with a large-Russian speaking community — fighting between the rebels and Ukraine's forces killed thousands of people.

A fragile ceasefire has been in place since last year, but there is no permanent settlement to the conflict.

AFP/Reuters