Reviewing the status of a key Russian naval base in Ukraine could reignite a potentially dangerous border row. That was the warning from Russian defence minister Sergei Ivanov to Kiev after it threatened to reconsider the agreement to let Moscow lease the Sevastopol base in the Crimean peninsula for about 80 euros a year.It came after Russia hiked gas prices by more than 400 per cent. Ivanov said the agreement over the base is one part of a bilateral treaty, the second part of which contains recognition of mutual borders. He added that trying to revise the treaty would be fatal. Crimea was handed over to Ukraine in a symbolic gesture by the Soviet Union in the 1950s. After its collapse in 1991 Russian nationalists staged a fierce campaign to take it back. Russia’s gas monopoly Gazprom has demanded Ukraine pay nearly 200 euros per 1,000 cubic metres of gas, up from this year’s 42 euros. Ukrainian president Viktor Yushchenko apparently sees the rise as a punishment for Kiev’s pro-Western policies.