By Christian Lowe

MOSCOW, May 30 (Reuters) - The United States and the European Union launch a diplomatic drive next week to try to calm tensions over Georgia's breakaway region Abkhazia that some observers say have come close to igniting a war.

The conflict over the rebel territory on Georgia's Black Sea coast has also become a major source of friction between Russia, which backs the separatists, and the West, which supports Georgia and wants to see it eventually join NATO.

EU foreign policy chief Javier Solana is expected to visit Tbilisi and Abkhazia next week, while U.S. Deputy Assistant Secretary of State Matthew Bryza, Washington's point man for the region, will come to Moscow.

A delegation of ambassadors from EU member states travelled to the separatist capital, Sukhumi, on Friday.

"We are ... concerned about the tension ... around Abkhazia lately," said Peter Semneby, the EU special representative for the South Caucasus, the region on Russia's southern flank that includes Georgia.

The EU wants first to find a way of lowering the tension, and then "to see what can be done to eventually move towards a resolution of the conflict," he told Reuters.

The heightened Western interest in Abkhazia follows a United Nations report last week that concluded a Russian jet shot down an unmanned Georgian spy plane over the region in April.

Moscow denies involvement, but the incident followed Russian moves -- including sending in extra troops and intensifying ties with the separatists -- that Tbilisi says amount to a creeping annexation of Abkhazia.

Vladimir Putin, at the time Russian president, said he acted to protect the Abkhaz people from an imminent Georgian attack. Some observers say he was in fact punishing the West for recognising Kosovo and Georgia for seeking NATO membership.

The South Caucasus has remained unstable since Abkhazia drove out Georgian forces in the 1990s, worrying the West which sees the region as a vital part of an energy corridor between the Caspian Sea oil fields and world markets.

MESSAGE TO MOSCOW

A Tbilisi-based diplomat said one aim of Solana's visit was to show Moscow the EU is watching Abkhazia closely.

"It's a demonstration the EU is concerned about the situation," the diplomat told Reuters. "It is happening against the background of ... what the Georgians feel is a very serious challenge to them by the Russians."

The next step is a meeting in early June in St Petersburg between Georgian President Mikheil Saakashvili and Russia's Dmitry Medvedev, their first contact since Medvedev became president.

"Nobody really knows what Medvedev thinks about this (Abkhazia)," said the Tbilisi-based diplomat. "There is a key issue: what do the Russians now want?"

Georgian officials expressed hope Solana's visit would help persuade Russia to soften its stance on Abkhazia.

"The main aim of Solana's visit ... is the settlement of the crisis between Georgia and Russia as that's the main problem right now," said Giga Bokeria, a deputy foreign minister.

Solana will also encourage Tbilisi's tentative dialogue with the separatists, launched at the height of the row earlier this month when a Georgian envoy held secret talks in Abkhazia.

Most observers believe an interim peace deal may be on the table, possibly involving security guarantees for the Abkhaz, the return of ethnic Georgian refugees and measures to protect Georgia's sovereignty.

Separatist foreign minister Sergei Shamba was sceptical about the chance of progress. "That will depend on the Georgian position," he told Reuters. "The ball is in their court."

AlertNet news is provided by