Russia mocks Western appeals to end Azov Sea crisis

"This [sanctions] has long ceased to concern us," he said, accusing some in the West of being "obsessed only with the desire to look for more and more new reasons for putting pressure on Russia".

He accused Ukraine of having "provoked" the incident "in the hope that the US and Europe, as always, recklessly, will take [its] side".

He also scoffed at EU calls for Russia to stop harassing commercial ships trying to reach Ukrainian ports in the region, saying Russia's inspections of the vessels were "in full compliance" with maritime treaties.

The Russian foreign ministry went further in its statement, saying that the attempt at "provoking a conflict with Russia" was carried out by Ukraine "in coordination with the United States and the European Union".

Ukraine, on Sunday, accused Russia of an unprovoked attack on three of its ships, including live fire which injured a handful of seamen.

Its account was fully corroborated by the US and EU.

"Russia rams Ukrainian vessel peacefully traveling toward a Ukrainian port. Russia seizes ships and crew and then accuses Ukraine of provocation," the US special envoy to Ukraine, Kurt Volker, said.

"I condemn Russian use of force in Azov Sea," Donald Tusk, the EU Council president, added.

But Russian authorities and state media said it was Ukraine which caused the situation, because its ships had performed "dangerous manoeuvres" in a zone that had been "temporarily closed" by Russia in a heavily-militarised area after Russia seized Crimea from Ukraine in 2014.

Elections

The Kremlin spokesman, Dmitry Peskov, added that Ukraine did it so that its president, Petro Poroshenko, could put off elections by imposing martial law because he was not doing very well in polls.

"Such a decision certainly smells of electoral intrigues," Peskov said.

For his part, Poroshenko announced the martial law move on Monday, pending parliamentary approval.

But his decree made no mention of elections, which are due in March 2019 - well after the 60-day period of his martial act is due to end.

The clash has raised alarm in Europe that the four-year old Ukrainian conflict could escalate into full-blown war, prompting snap meetings at the UN and Nato on Monday.

The leading EU powers - France, Germany, and the UK - voiced concern and urged Russia to free Ukraine's vessels, but did not threaten new sanctions, despite calls for such a move by Lithuania and Poland.

The German foreign minister, Heiko Mass, also said "we will mediate so that this conflict does not turn into a serious crisis".

But Ukraine's foreign minister, Pavlo Klimkin, said "Ukraine will seek to settle the row in a peaceful manner", even though its armed forces have been put on alert.

Flags and camo

Western experts and politicians also said the escalation was unlikely to go too far.

"Russia is ... shooting darts ahead of the 2019 [Ukrainian] presidential election that will make Poroshenko look weak," Roderich Kiesewetter, an MP from the ruling CDU party in Germany, said.

Russian leader Vladimir Putin needed a new international drama to shore up his falling popularity at home, Russian opposition activist Alexei Navalny noted.

The "tragic irony" was that both Putin and Poroshenko were likely to exploit the crisis for "political posturing" by "draping themselves in flags and camouflage [uniforms]" for TV cameras, Mark Galeotti, a British expert on Russian affairs at the European University Institute in Florence, said.