By Elena Teslova

MOSCOW

Russia late Sunday admitted that it seized three Ukrainian vessels off Crimea after they ignored the "demands to stop", according to the country's federal service. 

“Berdyansk”, “Nikopol” and “Yany Kapu” vessels didn’t respond to the Russian border service's demands to stop, and therefore, Russian military "had to use the weapons to stop them", FSB said in a statement. 

FSB said Russia has launched a criminal investigation into the "violation of the Russian state border.”

Three Ukrainian sailors suffered non-life threatening injuries during the incident, and they received medical treatment, it said. 

The Ukrainian Navy earlier accused Russia of opening fire on its warships off Crimea, asserting that crew members were wounded and its vessels were seized by Russia. 

'Bandit methods'

Russian Foreign Ministry Spokesperson Maria Zakharova called the Ukrainian Navy move in the Kerch Strait as a "provocation".

On official Facebook page, Zakharova blamed the Ukrainian government for using “bandit methods”.

“First the provocation, then the power pressure, and then the charge of aggression,” Zakharova wrote.

Russian fighter jets Su-25 patrol the Kerch Strait after the incident while the strait has also been closed for the civil vessels.

Meanwhile, Ukrainian local media claimed that one person was killed on the fire.

Following the crisis, Svyatoslav Tsegolko, press secretary of the Ukrainian President, said on Twitter that Petro Poroshenko is convening a military cabinet due to "extraordinary incident."

Earlier in the day, Russia intervened as Ukrainian warships were engaged in relocation from the Port of Odessa to the Port of Mariupol in the Sea of Azov.