Three United Nations observers and their interpreter have been kidnapped while patrolling a buffer zone in Georgia.
A truck carrying the monitors and Russian soldiers was said to have been fired upon by unknown gunmen as it travelled through the troubled Kodori Gorge area bordering the breakaway region of Abkhazia.
A UN spokeswoman told BBC News Online: "Three military observers and an interpreter were kidnapped in the Georgian-controlled part of Kodori at 10.25am local time.
"We are working closely with the Georgian authorities to resolve this."
She had no information on the nationalities of those abducted, although Reuters news agency quoted a UN official in the Georgian capital Tbilisi as saying one of the observers was German.
Peace talks stalled
Around 100 UN monitors have been observing a truce agreement between Georgian troops and Abkhaz rebels in the Kodori Gorge region.
Abkhazia has had de facto independence from Georgia since 1993 - following a bitter two-year war with Georgian troops - but it is not recognised as an independent state.
UN-sponsored peace talks have stalled and there is still sporadic fighting across the border zone.
Two years ago, nine UN observers and crew were killed when their helicopter was shot down in the area. The attack was blamed on rebels from neighbouring Chechnya in Abkhazia.
UN monitors have been kidnapped in Georgia on three previous occasions - the last time in 2000 - and released following negotiations.
Emzar Kvitsiani, the Georgian President's representative in the Kodori Gorge, told the Russian news agency Itar-Tass he was going to the area and would take all necessary steps to free the hostages.
He was earlier quoted as saying Georgian and Abkhazian officials were due on Thursday to sign an agreement on the return of ethnic Georgian refugees to the breakaway region.
"It looks like somebody really does not want peace in the conflict area," he reportedly said.