By Maria Tsvetkova and Dmitry Solovyov
MOSCOW (Reuters) - Ukrainian President Petro Poroshenko was flying to Russia on Wednesday to bring home detained Ukrainian servicewoman Nadiya Savchenko, in exchange for the release of two Russians held by Kiev, Russian media and a source close to the swap said.
Handing over Savchenko, whose release has been demanded by Western governments and who has become a national hero in Ukraine, would ease tensions between Moscow and the West a few weeks before the European Union decides whether to extend sanctions on Russia.
Russia's Interfax news agency quoted an unnamed source as saying Poroshenko's aircraft was en route to the southern Russian city of Rostov-on-Don.
On board his plane, the agency said, were Yevgeny Yerofeyev and Alexander Alexandrov, who both told Reuters in interviews last year they are Russian special forces soldiers who were captured while carrying out a secret operation in eastern Ukraine.
The plan, according to the source quoted by Interfax, was for Poroshenko to deliver the two Russians and pick up Savchenko and take her home.
Asked by Reuters if the exchange was now underway, a source close to the arrangements said: "Yes."
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.
A Russian court in March sentenced her to 22 years in jail. While in Russian jail, she was elected a member of the Ukrainian parliament and is widely seen in Ukraine as a symbol of resistance against Russia.
(Writing by Christian Lowe; Editing by Dmitry Solovyov)