– The Ukrainian government and Russia-backed separatists completed an exchange of prisoners Saturday, starting a process outlined in a truce brokered by international leaders.

A rebel representative said 139 Ukrainian troops and 52 rebels were swapped.

Ukrainian President Petro Poroshenko wrote on his Twitter account that he was informed the process had begun by the national security service.

The peace agreement signed Feb. 12 foresees an exchange of all prisoners in the conflict. It is unclear how many are held by both sides, although the Donetsk separatists have said Ukraine is holding about 580 rebels as prisoners.

Elsewhere Saturday, Ukraine's military and the Russia-backed rebels accused each other of continuing to mount attacks.

Ukrainian security spokesman Col. Andriy Lysenko said that one serviceman was killed and 40 wounded in attacks over the past day. He said there were 10 mortar attacks on Ukrainian forces in the village of Shyrokyne on the fringes of the port city of Mariupol.

Lysenko said rebels continued to move equipment toward Mariupol. Concerns persist that rebels aim to seize the city, which would give them a land corridor between mainland Russia and the Russia-annexed Crimea peninsula.

Rebels claimed that Ukrainian forces launched 15 attacks overnight Friday.

Associated Press