Philippines Foreign Minister Albert del Rosario told the news agency Reuters that the four UN peacekeepers, all Filipinos, had been released. Rebels detained them May 7 as they patrolled close to an area where the same group held 21 observers, also Filipinos, for three days in March.

In a statement, UN Secretary-General Koffi Annan said that he appreciated "the assistance of Qatar and of others involved in securing their safe release," and emphasized "to all parties the impartiality of United Nations peacekeepers."

The rebel Yarmouk Martyrs Brigade had announced that it had taken the peacekeepers into custody for their own safety after clashes in the area put them in danger. The rebel group had no immediate announcement after the peacekeepers' release on Sunday.

Saturday's blasts have raised concern that Syria's bloody civil war is crossing into Turkey, too. The two explosions, just 15 minutes apart, occurred Saturday outside the post office and town hall in Reyhanli, a hub for Syrian refugees and rebel activity in Turkey's Hatay province.

At least 43 people were killed in the blasts and about 100 injured, Deputy Prime Minister Bulent Arinc said. He added that authorities were still investigating the attacks, but said Syria's intelligence and military were "the usual suspects" behind the bombings.

Syria has denied any involvement.

mkg/rc (Reuters, AFP, dpa, AP)