The Organization for Security and Cooperation in Europe (OSCE) announced on Saturday that four further observers from the Special Monitoring Mission in Ukraine had been released from Luhansk after being held for a month by pro-Russian separatists.
"The entire OSCE family welcomes the safe and long-awaited release of our monitors," said OSCE Secretary General Lamberto Zannier in a statement on the OSCE website. "They volunteered to help Ukraine at a critical moment in its history. We are proud of their contribution, and we admire their courage in the face of very difficult circumstances."
Late on Thursday, a different group of four OSCE observers had been released from their 32-day captivity in Donetsk.
At a summit of the European Union on Friday, EU officials had demanded that the rebels release all hostages, including international OSCE observers.
"We have fulfilled our obligations before the Ukrainian side," Alexander Borodai, a rebel leader, told the Interfax news agency on Saturday. "All eight observers have been released."
The release of the final observers came a day after Ukrainian President Petro Poroshenko announced an extended cease-fire between government troops and separatist rebels in eastern Ukraine.
Despite the cease-fire extension, three Ukrainian soldiers died in clashes near the eastern city of Slovyansk on Saturday, the military said.
"As a result of the (rebel) fighters shooting at the post near Slovyansk, three members of the Ukrainian forces were killed and a fourth was wounded," Ukrainian military spokesperson Oleksiy Dmitrashkovsky was quoted as saying by the Interfax news agency.
The troops were part of Ukraine's "anti-terrorist operation," Dmitrashkovsky said, and were occupying a post near Slovyansk when they were attacked with small arms and mortar fire.
EU increases pressure
A week-long cease-fire between the Ukrainian military and pro-Russian rebels expired on Friday night but was extended by 72 hours. Poroshenko extended the tenuous truce when he returned to Kyiv from Friday's summit in Brussels, where he signed a landmark Ukrainian free trade and political association deal with the EU, despite Russian objections.
The EU summit on Friday also demanded that the rebels start substantial talks on a peace plan.
The 15-point plan was outlined by Poroshenko a week ago but the rebels refused to lay down their arms.
Donetsk separatist leader Miroslav Rudenko claimed that government troops were using the extension - which runs until 1900 UTC Monday - to strengthen their positions.
mz/kms (Reuters, AP, AFP, dpa)