Victor Yushchenko, on Wednesday announced restrictions on use of the Crimean port of Sevastopol by Russia’s Black Sea Fleet, a move that follows a challenge by Kiev this week to Moscow’s naval operations off Georgia’s coast.

The surprise decree by Ukraine’s pro-western president requires Russian naval vessels to request permission 10 days in advance before returning to the strategically important port, which Russia leases from Ukraine. Russia’s defence ministry quickly denounced it as “not serious”.