Swiss President and OSCE chief Didier Burkhalter on Friday hailed the release of four of the organization’s observers abducted in east Ukraine a month ago, but demanded the freeing of others still being held

Swiss President and OSCE chief Didier Burkhalter on Friday hailed the release of four of the organization’s observers abducted in east Ukraine a month ago, but demanded the freeing of others still being held.
  
Burkhalter expressed "his gratitude to all who helped in setting four of the eight monitors of the OSCE Special Monitoring Mission free," his office said in a statement.

The comment came after a separatist leader announced that the four monitors, who were abducted on May 26 by pro-Russian rebels had been freed. "They have been freed without conditions. They are a Dane, a Turk, a Swiss national and I believe an Estonian," said Alexandre Borodai, the "prime minister" of the self-proclaimed Republic of Donetsk, which has declared independence from the Kiev government after a disputed referendum. He said they had been held by a rebel chief in the neighboring restive region of Lugansk.

While welcoming the release, and thanking all countries that contributed to securing it, Burkhalter stressed that four more Lugansk-based observers were still missing. He demanded the "speedy and unconditional release" of them and the many others "held hostage in the east of Ukraine," according to the statement.
  
Rebel leaders for their part claim that they do not control the actions of all the militias in their region fighting against the Ukrainian forces.