TBILISI, Nov 10 (Reuters) - An explosion killed two Georgian police officers near breakaway South Ossetia on Monday, drawing a call for calm from EU ceasefire monitors already concerned over an alleged border incursion at the weekend.

The head of the EU mission monitoring the ceasefire said the explosion marked "an unacceptable breach" of the pact brokered between Georgia and Russia after Moscow fought off a Georgian bid to retake the rebel region in August.

"Today's attack risks escalating the still tense situation along the administrative boundary lines," EU mission head Hansjoerg Haber said in a statement.

The statement blamed an improvised explosive device and said the incident "reportedly was accompanied by gunfire".

More than 200 unarmed EU monitors are observing the ceasefire, already strained by accusations of border attacks and kidnappings from both sides since the Russian pullback.

But a Georgian Interior Ministry spokesman said there was no indication of incoming gunfire.

Georgian police said the two officers were killed when a landmine exploded during a patrol near the village of Dvani, in what was until early October a Russian-controlled buffer zone.

Three other officers were wounded, one seriously, in a second blast when they tried to extract their colleagues.

On Sunday, Georgia accused South Ossetian forces of taking control of a Georgian village outside the de facto borders of the separatist territory.

Georgia said South Ossetian security forces were moving into the village of Perevi on the territory's western flank to replace a Russian checkpoint that was withdrawing.

Russian troops pulled back from a buffer zone around South Ossetia in early October, but kept one checkpoint in Perevi, a village of around 1,000 people west of the boundary.

South Ossetia said its forces had deployed only in part of the village within its borders.

A spokesman for the EU monitors said they were unable to "verify the makeup" of the Perevi checkpoint, saying there were reports Russian commanders were still in charge. (Reporting by Matt Robinson and Margarita Antidze; editing by Elizabeth Piper)

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