Ukrainian President Petro Poroshenko said on Sunday he hoped to see a Kiev-born pilot who received a 14-year jail sentence in Russia return home as part of a prisoner swap "in a few weeks".

The case of 34-year-old Nadiya Savchenko has further strained ties between the two neighbours as Ukraine fights a pro-Russian eastern insurgency that Moscow denies backing, despite evidence of its troops entering the war zone.

Poroshenko said last Tuesday that he had telephoned Russian President Vladimir Putin and appeared to have a struck a deal in which Savchenko would be swapped for two alleged Russian soldiers captured and convicted in Ukraine.

But Poroshenko sounded more certain about such an exchange on Sunday.

"We agreed a formula for resolving this problem. We agreed on its preliminary terms," the pro-Western leader said during a televised interview.

"And right now, I firmly hope that the presidential plane with my representatives will return Nadiya to Ukraine in a few weeks."

There was no immediate response to Poroshenko's comments from the Kremlin.Savchenko -- who has become a national heroine in a case that has drawn Western governments' concern -- was jailed in March after being convicted of the murder of two Russian journalists who died covering the two-year rebellion.

She denies the charges and has staged a number of hunger strikes in protest.

A long-mooted exchange of Savchenko for the Russian prisoners appeared closer at hand after a court in Kiev last Monday convicted the two Russians of fighting alongside the rebels.

Sergeant Aleksander Aleksandrov and captain Yevgeny Yerofeyev received 14-year jail terms that they have decided not to appeal -- a move that may speed up the possible swap.

Ukraine insists the two fighters were serving members of an elite Russian military intelligence unit when they were captured in May last year.

Moscow says they had quit the army before crossing the border.

Kiev and Moscow have been locked in a bitter feud over the Kremlin's 2014 annexation of Crimea and alleged responsibility for a war that has left nearly 9,200 people dead.

Source :AFP