Russian Prime Minister Mikhail Kasyanov has called for the suspension for several days of work on a causeway near the sea border with Ukraine, the building of which has caused tension between the two countries.
Passions are running high in Kiev over the dispute
Mr Kasyanov's spokeswoman Tatyana Razbash said she did not know whether the local authorities in the southern Krasnodar territory had complied with the request.
The dispute has been escalating in recent days, and earlier on Wednesday Ukrainian President Leonid Kuchma cut short a foreign trip to address the crisis.
Kiev is angry that Russia is building the causeway towards a Ukrainian island near the Black Sea.
Russia has also asked for proof that the island, Tuzla, is legally part of Ukraine.
Russia says the causeway is essential to protect part of its territory from coastal erosion.
Ukrainian officials said the causeway had already got to within hundreds of metres of Ukrainian territorial waters.
The dispute threatens to derail the new common market agreement the two countries have concluded with Belarus and Kazakhstan.
Mr Kuchma announced in Brazil that the rest of his state visit to Latin American was being abandoned.
"In connection with growing tensions around Tuzla island,
President Leonid Kuchma decided to cut his state visit to Latin
American countries," said a statement from the presidential press service.
Officials in Moscow say the issue will be discussed in a meeting between the two countries' foreign ministers on 30 October.
The causeway, which was begun on 19 September, is expected to reach Ukrainian territorial waters by 26 October.
It is being built in the Kerch Strait, which separates Ukraine's Crimea region from the Taman peninsula and runs between the Black Sea and the Azov Sea.
But Ukrainian foreign ministry spokesman Markian Lubkivsky said on Tuesday that Kiev would never allow it to be finished.
Ukraine has put its border guards on alert, laid tank traps on the island and held air and sea exercises nearby.
Correspondents say Ukraine is worried that Russia will try to claim more territory ahead of the talks.
However, Russian Foreign Minister Igor Ivanov said the causeway was being built purely for economic and environmental reasons. "There are no reasons to fan passions," he said.
Some Russian officials have cast doubt on Ukraine's claim to Tuzla.
The causeway is being built for economic and environmental reasons, says Russia
The chairman of the State Duma's International Affairs Committee, Dmitry Rogozin, said Ukraine had drawn an arbitrary border line on the waters between Tuzla and the Taman peninsula in an attempt to push Russia out of the Kerch Strait.
The parliaments of both countries were discussing the issue on Wednesday.
The growing row has sparked an angry response in Ukrainian newspapers, with some accusing Russia of still seeing Ukraine as an "economic colony" within its empire, or of trying trying gain free sea passage rights.
"Only when the neighbour has blatantly extended its hand to grab (Tuzla) have we realized how dear our motherland is to us," said Moloda newspaper.
Russian papers also saw the situation as very serious.
"In the next few days the Ukrainian-Russian dispute in the Kerch Strait could escalate into an armed conflict. And this is not an exaggeration," says Nezavisimaya Gazeta.