Russia has accused Ukraine of "dangerous" moves and deliberately provoking an incident in the Kerch Strait near Crimea in which Russia seized three Ukrainian vessels.

Russian Foreign Minister Sergei Lavrov on Monday said Ukraine had violated international norms with "dangerous methods that created threats and risks for the normal movement of ships in the area."

Foreign Ministry spokeswoman Maria Zakharova said Moscow will summon a senior Ukrainian diplomat to complain about the incident.

Russia on Sunday seized two Ukrainian armored artillery vessels and a tug boat, saying they had illegally entered Russia's territorial waters.

The flotilla, it said, had not notified Russia of its plans in advance and ignored warnings to stop while maneuvering dangerously.

Russian officials said they reopened the Kerch Strait to shipping in the early hours of Monday morning. Ships use the Kerch Strait for passage from the Black Sea into the Sea of Azov.

The Sea of Azov is a strategic ocean route linked to the Black Sea by the narrow Strait of Kerch where Russia has built a bridge to link the Crimean Peninsula with the mainland.

Tensions escalated earlier this year after Ukraine detained two Russian ships for port calls on Crimea, which rejoined Russia in a 2014 referendum.

The move prompted Russia to increase patrols off its Azov coast to guarantee free navigation by Russian ships.

With relations still rocky, the incident risks pushing the two countries towards a wider conflict and is likely to renew Western calls for more sanctions on Moscow.

On Sunday, Ukrainian President Petro Poroshenko held an emergency meeting with ministers and army officials and proposed the introduction of martial law in response to what he describes as Russia’s “growing aggression.”

It was not clear what the introduction of martial law would entail, including inside Ukraine, but Poroshenko emphasized that he did not want to go to another war with Russia.

“Martial law doesn’t mean declaration of war. Ukraine doesn’t plan to start war against anyone, we are just reacting in favor of defending our land and territory, as well as the sovereignty and independence of Ukraine,” he said.

“This doesn’t prevent us from using diplomatic and political means to protect Ukrainian territory,” he said, demanding that Russia release the Ukrainian vessels.

Lawmakers were due to vote later Monday on declaring martial law.

Any decision to impose martial law in Ukraine would be unpopular as it would curb civil liberties and give state institutions greater power ahead of a presidential election next year which polls indicate Poroshenko would lose.

Russian fighter jets fly over a bridge connecting the Russian mainland with the Crimean Peninsula, in the Black Sea, on November 25, 2018. (Photo by Reuters)

Zakharova on Monday accused Ukraine of sending the ships to deliberately provoke Russia which has warned the West against escalating tensions in the Sea of Azov to impose new sanctions on Moscow.

On Friday, Lavrov said "our European colleagues" were attempting "to invent yet another pretext for putting pressure on the Russian Federation.”

Several Western governments rallied behind Ukraine on Monday. "Western governments will side with Ukraine against Russia over the incident... making new sanctions against Russia likely," research firm Eurasia Group said.

The European Union called on Russia to restore freedom of passage via the Kerch Strait and urged both sides to act with the utmost restraint. A NATO spokeswoman issued a similar appeal to both sides.

Danish Foreign Minister Anders Samuelsen said on Twitter his country gave its full support to Ukraine, while Poland accused Russia of breaching international rules through "its aggressive behavior".

German Foreign Minister Heiko Maas said the developments were "troubling" and urged the easing of the tensions.

"A Russian blockade of the passage to the Sea of Azov is unacceptable. It is important that the blockade be lifted. We call on both sides to deescalate," he said.