Russia warned neighboring Ukraine on Tuesday of grave consequences if it seeks to revise the terms of a deal on a Russia-leased Crimean port.
"To subject these agreements to revision is fatal," Deputy Prime Minister and Defense Minister Sergei Ivanov was quoted by the Itar-Tass news agency as saying.
"The Black Sea Fleet accords are an integral part of the big Russia-Ukraine treaty of 1997," which contains agreements on recognition of each other's territorial borders, Ivanov also said.
In mid-1990s, Russia and Ukraine divided up the Soviet Black Sea Fleet after anguished talks. Under the deal, Russia leases the Sevastopol port in Ukraine's Crimea peninsula to base its ships until 2017.
But many Ukrainian politicians consider too low the annual rent of 98 million U.S. dollars paid by Russia. Kiev has said it might review the leasing terms.
Ivanov pointed out that the rent was set under the basic agreements and should remain unchanged until 2017, and Russia pays for utility and transport services and contributes 60 percent of revenue to Sevastopol's budget.
The two nations have been locked in a bitter dispute over gas prices with Russia asking Ukraine to pay more than quadruple the current price for gas it buys from Russia.
Earlier this month, Ukrainian President Viktor Yushchenko linked gas-supply talks with Russia to a review of the Crimean port rent.