Rebels release four international observers captured over a month ago in Ukraine.

Eight of them were detained in May as they were monitoring an agreement aimed at calming the conflict.

The four were handed over to colleagues at a hotel early on Friday.

The prime minister of the rebels' Donetsk People's Republic says there are no pre-conditions for the release.

(SOUNDBITE) (Russian) ALEXANDER BORODAI, PRIME MINISTER OF THE SELF-STYLED DONETSK PEOPLE REPUBLIC, STANDING SURROUNDED BY REBELS AND SAYING:

"It was a long road and this release is the fruit of goodwill and it was unconditional."

The remaining four are still in captivity. The pro-Russian separatists have said they hope to secure their release soon.