Georgia and Russia say Caucasus talks constructive

* Georgia and Russia to keep discussing deal to avoid force * More talks planned on Abkhazia, South Ossetia security

* Geneva negotiations aimed at preventing another flare-up By Laura MacInnis and Stephanie Nebehay GENEVA, July 1 (Reuters) - Georgian and Russian officials held strained but constructive talks on Wednesday about ways to avoid more conflict in the volatile Caucasus region, international mediators said.

Talks to prevent a repeat of last year's flare-up would continue despite heightened Moscow-Tbilisi tensions, a joint statement by mediators from the European Union, United Nations and Organisation for Security and Cooperation in Europe said.

More negotiations will take place in Abkhazia's eastern Gali region on July 14 and in Geneva on Sept. 17, they said.

On Tuesday, U.N. monitors began pulling out of Georgia and the OSCE closed its observer mission, raising concerns about a security vacuum in the key transit territory for Caspian gas and oil where a five-day war erupted in August 2008. [ID:nLU99002]

"We had discussions that were substantive," Pierre Morel, EU special representative for the Georgia crisis, told a news briefing.

United Nations mediator Johan Verbeke said the latest set of talks "set the groundwork" for deals on avoiding use of force in the region and on the role of international security forces.

Charalampos Christopoulos of Greece said on behalf of the OSCE that all sides had agreed to work to improve access to drinking and irrigation water in the hotly disputed areas.

"It is vitally important to swiftly address the problems of potable and irrigation water in the region to help the local people irrespective of their ethnic origin," he said.

Tensions remain high nearly a year on from the Caucasus conflict, after which Russia recognised breakaway Abkhazia and South Ossetia as independent states and stationed thousands of troops in both regions.

Earlier this week, Moscow raised Georgian stress levels by launching large-scale military exercises in its strategically important southern region [ID:nLT135192].

(Editing by Elizabeth Fullerton)