Russia Accuses Ukraine of Provocation and 'Dangerous' Moves As Kiev Demands Return of Sailors and Boats

Russia has accused Ukraine of violating international law, "dangerous" moves and planning a flare-up of tensions between the two countries after a stand-off in the Black Sea.

The comments by Russian foreign minister Sergey Lavrov came as Ukraine's president Petro Poroshenko demanded the release and safe return of its sailors and boats after a confrontation in the strategically important Kerch Strait.

Mr Poroshenko has signed a decree to introduce martial law for two months in response to what he described as Russian aggression.

Such martial law measures may include closing borders, imposing restrictions on foreigners entering the country, a ban on gun sales, a ban of political gatherings and rallies and shutting media outlets if they are deemed a threat to national security.

Six seamen were hurt on Sunday when Russian coast guards opened fire on two Ukrainian navy artillery boats and a navy tugboat, which were then seized.

Russia said three Ukrainian sailors were lightly injured and given medical assistance, and it had acted within international law during the confrontation.

Earlier that day, a Russian coast guard vessel appeared to ram the tugboat which was travelling with the artillery boats from Odessa on the Black Sea to Mariupol in the Sea of Azov, via the Strait.

Ukraine said the tugboat's engine, hull, side railing and a lifeboat were damaged in the collision near the Crimea peninsula that Moscow annexed from Ukraine in 2014.

Russia has placed a huge cargo ship beneath the Russian-controlled Kerch Strait bridge to block Ukrainian boats from access to the Sea of Azov.

And the Kremlin accused the Ukrainian vessels of illegally intruding into Russian territorial waters and of ignoring attempts by Russian border guards to contact them.

But Kiev said its vessels did nothing wrong and has accused Russia of military aggression.

It said its vessels were heading to the Sea of Azov in line with international maritime rules, while Russia said Kiev had failed to obtain permission to pass through the Strait separating Crimea from the Russian mainland.

Mr Lavrov hit out at Ukraine, saying "key norms of international law have been violated".

He went on: "It may be that while Ukraine was planning this provocation - and no one has any doubt that this was done with the goodwill and probably a direct order from the highest leadership (of Ukraine) - they were counting on additional benefits they wanted to get out of this situation.

"First of all they were counting on the fact that the US and Europe, as always, will recklessly take the side of the provocateurs."

And Mr Lavrov claimed the confrontation was a provocation "to serve as a pretext to impose further sanctions on Moscow", adding the European Union had "blind support" for Ukraine.

Russia's Federal Security Service (FSB) said it used weapons after the Ukrainian ships ignored demands to stop and that it impounded three vessels which had illegally crossed the border.

An emergency meeting of the United Nations Security Council has been called for later on Monday.

Meanwhile, president of the European Council Donald Tusk has tweeted: "I condemn Russian use of force in Azov Sea. Russian authorities must return Ukrainian sailors, vessels and refrain from further provocations."

He added: "Europe will stay united in support of Ukraine."

The European Commission's stressed that the bloc does not recognise Russia's annexation of Crimea and said Russia was obliged to unblock the Kerch Strait swiftly.

"We are taking this very seriously," a spokeswoman said.

Sky's foreign affairs editor Deborah Haynes said: "Tensions have been building up in the Azov Sea since Crimea was annexed. But what's happened over the last 24 hours is a really significant development.