Russia has allowed some ships to enter Ukrainian ports on the Sea of Azov, Kyiv confirmed on Thursday.

Ukrainian Infrastructure Minister Volodymyr Omelyan said merchant vessels were moving through the Kerch Strait, which links the Sea of Azov with the Black Sea, and the ports of Berdyansk and Mariupol have been "partially unblocked" thanks to a "stern international response."

However, the minister also said that 17 ships were still waiting to enter the Sea of Azov and one was waiting to leave. He said he hoped the full access would be restored in the coming days.

Last week, Omelyan accused Russia of blockading cargo ships from entering or leaving the ports after a naval confrontation that involved Russia seizing three Ukrainian naval ships and 24 seamen. Russia has denied blocking vessels in the Kerch Strait, saying any possible disruptions were due to bad weather.

Read more: What you need to know about the conflict in the Sea of Azov

Relations between Russia and Ukraine have been tense in recent years after Russian-backed separatists annexed the Crimean peninsula in 2014. Russia completed a bridge between the peninsula and its mainland earlier this year.

Ukrainian foreign minister Pavlo Klimkin was set to with his NATO counterparts on Tuesday seeking international backing with its current standoff with Russia.

dv/rc (AFP, AP, dpa)