SUKHUMI, Georgia, June 30 (Reuters) - Georgia's breakaway Abkhazia region said on Monday it was sealing itself off from Georgian-controlled territory after a series of explosions that it blamed on Tbilisi.

An official in the Georgian government denied any involvement in the explosions -- the latest of which injured a Russian holidaymaker on Monday -- and said Abkhazia's allegations were "politically-motivated".

Abkhazia, a region on the Black Sea coast, has been the scene of mounting tensions between Tbilisi's Western-leaning government, which wants to restore its control, and the Moscow-backed separatists.

Russia's Interfax news agency quoted separatist leader Sergei Bagapsh as saying the attacks were "terrorism pure and simple" and were the work of Georgian special forces.

"From Tuesday, the border with Georgia will be shut, and any movement across the Inguri river will be halted," Interfax quoted him as saying. The river separates southern Abkhazia from Georgian-controlled territory.

Six people, including the Russian holiday-maker, were lightly wounded on Monday after two bombs went off at a minibus stop in the separatist capital Sukhumi.

A local reporter told Reuters she saw a mangled rubbish bin and piles of broken glass at the scene.

Another six people -- all women -- were wounded in two blasts at a market in the nearby resort of Gagra on Sunday. One woman suffered an eye injury. Last Friday, a bomb exploded near a local United Nations mission, causing no injuries or damage.

"Taking into account yesterday's explosions, and as our President Sergei Bagapsh has said, these are acts of terror aimed at rocking stability and disrupting the tourist season," Sukhumi Mayor Alias Labakhua told Reuters.

"It's definitely Georgia which is behind all this -- they see our republic developing, strengthening ties with Russia."

Georgia rejected the charges. "We consider these accusations by the Abkhaz side to be purely politically motivated," said Shota Utiashvili, a senior official in the Georgian Interior Ministry.

In the past, Georgian officials have blamed attacks and blasts inside Abkhazia on local organised crime groups.

A popular Soviet-era resort, Abkhazia threw off Tbilisi's rule in a 1990s separatist war. It is not recognised by any state, but runs its own affairs.

Russia provides financial aid and has peacekeepers in the region, which it says are preventing further bloodshed. Georgia, an aspiring NATO member, accuses Moscow of trying to annexe Abkhazia.

Tensions escalated this year after Moscow established semi-official ties with Abkhazia and sent in extra troops. In one incident, the United Nations said a Russian jet shot down an unmanned Georgian spy plane, though Russia denied involvement.

Some observers say that if no solution is found, the conflict could jeopardise the 2014 Winter Olympics which Russia is hosting just a few kilometres from Abkhazia's border. (Additional reporting by Margarita Antidze in Tbilisi; Writing by Dmitry Solovyov; Editing by Elizabeth Piper)

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