By Natalia Antelava BBC, Tbilisi

Hundreds of ethnic Georgians in the breakaway province of South Ossetia have blocked the main roads in the area in a further escalation of tensions.

They are demanding the release of a Georgian policeman abducted on Thursday by the South Ossetian forces.

South Ossetian authorities say the policeman is a criminal.

They have also said that unidentified Georgian gunmen have abducted 12 South Ossetians, among them a high-ranking official.

Boris Chochiyev, the South Ossetian state minister, told the BBC that his deputy had been captured and severely beaten.

SOUTH OSSETIA Population: About 70,000 Capital: Tskhinvali Major languages: Ossetian, Georgian, Russian Major religion: Orthodox Christianity Currency: Russian rouble, Georgian lari

Georgian officials who are investigating the matter say they believe the abduction could be an act of revenge by the relatives of a Georgian policeman who was kidnapped by the South Ossetian forces last week.

He was abducted when South Ossetian gunmen attacked a Georgian police checkpoint.

The incident has fuelled new tensions in this volatile separatist province which wants independence from Georgia.