The confrontation over the Russian-Ukrainian border through the Azov and Black Seas and the Kerch Strait erupted in summer 2003 when Russia attempted to construct a dam on the Tuzla Island in the Kerch Strait. Ukraine accused Russia of encroaching on its territory and deployed border guards on the small island.
The Russian ministry said a Ukrainian proposal to change the status of the Azov Sea from territorial to international waters was unacceptable as it radically changed the situation in the talks.
The ministry said Russia remained committed to the agreement on the joint use of the Azov Sea and Kerch Strait signed in 2003 by Russian President Vladimir Putin and his then Ukrainian counterpart Leonid Kuchma. Under the agreement, the sea and the strait remained territorial waters of Russia and Ukraine.
Russian Ambassador-at-Large Valery Kenyaikin said Monday, "All agreements on this issue should follow from this  agreement, and not consist of reviewing the document."
He said then that the sides had managed to make progress on the issue of demarcating the Black Sea and adding that the Russian negotiators had submitted a draft agreement.
Ukrainian First Deputy Foreign Minister Anton Buteiko said Tuesday that Russia's refusal to sign the final protocol on demarcating the disputed border was politically motivated.
"We consider this reaction to be inappropriate as our proposals aimed to find a solution to the deadlock," he said, adding that Ukraine was surprised at Russia's reaction.