The protest follows a visit to Armenia last week by Russian Defence Minister Sergei Ivanov. He was quoted as saying that he planned to re-equip Russian troops based in Armenia, and to create joint Russian and Armenian military units.

"Such statements serve to change the balance of power in the south Caucasus and make an already difficult situation worse," said an Azeri foreign ministry statement.

"(They) cannot but give rise to justified concern from the Azeri side... We express our decisive protest," the statement added.

"Azerbaijan's foreign ministry calls on the Russian Federation not to increase Armenia's military strength and to take a constructive position to help build mutual trust between the peoples and states of the region."

Azerbaijan and Armenia, both former Soviet republics, fought a war in the early 1990s over the enclave of Nagorno-Karabakh. They are observing a ceasefire but a peace treaty was never signed.

Russia, along with France and the United States, has an international mandate to mediate between Armenia and Azerbaijan in the search for a peace deal over Nagorno-Karabakh.

However, many in official circles in Azerbaijan suspect the Kremlin of sympathising with the Armenian side. Russians and Armenians share the same Orthodox Christian faith, while Azerbaijan is predominantly Muslim.

WAR.WIRE