MOSCOW, February 26. /TASS/. Work on prisoner exchange under the all-for-all pattern remains priority for the Contact Group on Ukrainian settlement, Russian envoy to the group Boris Gryzlov told reporters after a new prisoner exchange earlier on Friday.

"As it was scheduled, a new, we can already say a next, prisoner exchange between Lugansk [People’s Republic] and the Kiev authorities took place on Friday. This means the release process continues despite the existing difficulties," the envoy said.

"This is one of the key humanitarian tasks of the Minsk process," the Russian envoy said.

Ukraine and the self-proclaimed Lugansk People’s Republic (LPR) exchanged prisoners in the six-for-three format earlier on Friday.

LPR’s representative in the Contact Group’s humanitarian subgroup Olga Kobtseva said Ukraine had released four women and two men and the LPR — three men.

"The prisoner exchange has taken place. We took a lot of efforts to have women released. Ukraine has once again violated the agreements reached in Minsk," she said, adding that it had been initially planned to conduct an exchange in the four-for-eight format. "Ukraine is responsible for these last-minute changes," Olga Kobtseva said.

Prisoner exchanges in the all-for-all format is one of the key provisions of the Package of Measures on the implementation of the Minsk agreements that was signed in the Belarusian capital Minsk on February 12 after marathon talks between the leaders of Russia, Germany, France and Ukraine.

The first prisoner exchange in 2016 took place on February 20 in the vicinity of the settlement of Maryinka near Donetsk. On that day, Ukraine released five militias of the self-proclaimed Donetsk People’s Republic (DPR) and a priest who was detained in the summer of 2015. The DPR released two communications officers of the Ukrainian army and a gunman from the Donbass paramilitary battalion.