A CRIMEAN court has ordered one of the Ukrainian seamen captured by Russia at the weekend to be held in custody for the next two months.

The seamen and their vessels were captured by Russian border guards late on Sunday as they were about to make their way through the Kerch Strait near Crimea.

Ukraine said its vessels were heading to the Sea of Azov in line with international maritime rules, while Russia claimed that they had failed to obtain permission to pass through the narrow Kerch Strait, which links the Azov with the Black Sea.

Russian news agencies reporting from a Crimean court yesterday quoted investigators as saying that the man faces charges of violating the border, which is punishable by up to six years in prison. The Ukrainian is to be held until January 26 at least.

It comes as the Kremlin warned that Ukraine’s declaration of martial law over the incident might trigger a flare-up in hostilities in eastern Ukraine, while Kiev blamed Russia for parading captured Ukrainian seamen on television.

The clash has raised the spectre of renewing a full-blown conflict in eastern Ukraine and saw Russia strongly criticised at the United Nations by the United States and its allies.

The Ukrainian parliament adopted a motion by the president on Monday to impose martial law for 30 days.

On Sunday near Crimea, Russian border guards rammed into and opened fire on three Ukrainian navy vessels travelling from the Black Sea towards a Ukrainian port, seizing the ships and their crews.

Ukraine considers the 24 captured men to be prisoners of war and says some have been seriously injured, while Russia says they are individuals who have violated its border.

The Kremlin reacted strongly to Ukraine’s declaration of martial law, with Dmitry Peskov, Vladimir Putin’s spokesman, telling reporters that it might trigger a flare-up in hostilities in eastern Ukraine.

Ukrainian troops have been fighting Russian-backed separatists in eastern Ukraine since 2014, leaving more than 10,000 dead, though fighting has eased since a truce in 2015.

The martial law formally went into effect on Monday in several parts of Ukraine, including areas bordering territory now held by the separatists.

The Russian intelligence agency FSB claimed the ships had Ukrainian SBU intelligence agents onboard with a mission to mount what they called “provocation” in the Kerch Strait.

The SBU confirmed that it had officers on the ships but denied any nefarious intentions, saying they were simply fulfilling counter-intelligence operations for the Ukrainian navy.

The SBU also demanded that Russia stop using “psychological and physical pressure” on the Ukrainians – an apparent reference to interviews with the crew members that Russia released late on Monday.

The video broadcast by Russian state television showed three separate interviews with Ukrainian seamen, all of whom agreed with Russian claims that they violated its border.

It was not immediately possible to ascertain if the men were talking under duress or had been subject to violence.

One of them was clearly reading from a script prepared for them.

Ukraine’s foreign minister said he has asked the president of the International Committee of the Red Cross to arrange a visit to the Ukrainian prisoners and he is waiting for a Russian response. Putin and German Chancellor Angela Merkel spoke on the phone early yesterday, and the Russian president expressed a “serious concern” about what the martial law in Ukraine might entail.

Meanwhile, German foreign minister Heiko Maas said Berlin has “called on Russia and Ukraine to show the greatest possible restraint” and suggested that Germany, France, Russia and Ukraine could work together to resolve the tensions.

Russian foreign minister Sergey Lavrov, who was visiting Paris, rejected that offer, saying that he did not see “a need for any kind of mediators”.

He spoke after meeting with French foreign minister Jean-Yves Le Drian, who appeared to soften his criticism of Russia’s seizure of the ships.

Shortly after Russian border guards seized the Ukrainian ships off Crimea, France’s Foreign Ministry said “nothing justifies” Russia’s use of force.

After talks with Lavrov, however, Le Drian blamed the stand-off on the “high level of militarisation” in the region and avoided blaming Russia.