The two countries have been locked in a bitter stand-off over the mountain territory for more than a decade, poisoning efforts to bring stability to the strategic South Caucasus region, bordered by Russia, Turkey and Iran.

Having gone to war in the early 1990s, their forces still clash sporadically and any escalation could derail Western efforts to promote a corridor of oil and gas pipelines from the Caspian Sea to Europe.

Russia and Turkey have a close interest. Ankara has closed its borders with Armenia in support of Azerbaijan, while Moscow counts Armenia as its closest ally among the ex-Soviet states on this southern flank.

Now however diplomats are saying that a meeting this weekend in the Russian city of Saint Petersburg between Armenian President Robert Kocharian and his Azerbaijani counterpart Ilham Aliyev could herald a breakthrough.