MOSCOW - The ambiguous status of a key Russian missile-tracking station in Azerbaijan, a major irritant in relations, is expected to be settled in a visit to Russia by Azeri leader Haydar Aliyev which began on Thursday.

The 78-year-old Azeri leader was due to meet President Vladimir Putin on Friday for talks also likely to touch on Caspian Sea oil exploration and the protracted dispute around the breakaway Azeri region of Nagorno-Karabakh.

But the signing of a deal settling the immediate future of the Soviet-built Gabala radar station in northern Azerbaijan, a key element in Russia's missile attack early warning system, seems certain to be the high point of Aliyev's three-day visit.

The status of the Gabala station, which can monitor inter-continental ballistic missile launches across the southern hemisphere, has stubbornly eluded settlement despite a trip to the Azerbaijan capital Baku by Putin almost exactly a year ago.

Sovereignty over the Gabala station was assumed by Azerbaijan when the oil-rich Transcaucasian country gained independence with the 1991 breakup of the Soviet Union. But it has remained in Russian operational hands.

After years of haggling over terms, Azerbaijan appears set to offer Moscow a 10-year lease on the installation though the sides have to agree on how much rent Russia will have to pay.
Azeri deputy prime minister Abbas Abbasov said in Baku that a deal formalising the status of Gabala would be one of eight accords signed during Aliyev's visit.

Western analysts say the deal is particularly important given the U.S. military campaign in Afghanistan and the Gabala station's role as a key lookout over a region that also includes India, Pakistan and the Gulf.

Aliyev, a political evergreen and former Soviet politburo member, is one of the wiliest political operators in the former Soviet Union, though there is a question mark over his health since he underwent heart bypass surgery in 1999.

He has used Azerbaijan's immense potential oil wealth and its strategic location to play off the regional big powers - Russia, Iran and NATO-member Turkey - against one another.

DIVIDING CASPIAN OIL WEALTH

Putin and Aliyev will also discuss how to divide the Caspian Sea's immense oil wealth. Russia and Azerbaijan mainly agree, but are both in dispute with Iran.

Russia, Azerbaijan and Kazakhstan want the Caspian to be divided according to the length of each country's coast, while Iran and Turkmenistan, with shorter coasts, want it to be divided equally among the five coastal states.

Commentators say Aliyev may ask Putin to use Russia's leverage to press Iran on the issue.

Russia is a co-chairman of the Organisation of Security and Cooperation in Europe's Minsk group which is trying to help Azerbaijan and Armenia work out a negotiated settlement to their long-running dispute over Nagorno-Karabakh.

The ethnic-Armenian territory broke away from Azerbaijan in 1988 in a humiliation for Azeri forces. Aliyev will be listening for any signs that Russia may be prepared to bring pressure to bear on Armenia for a settlement.