Iran has formally accused the US of deliberately striking two of its search-and-rescue vessels in the Persian Gulf, calling the attack a war crime. The accusation comes as the US maintains a blockade of Iranian ports and continues to attack the Iranian Navy.

The charges were made public in the letter on Friday, sent by Gholamhossein Darzi, Iran’s deputy envoy to the UN, to UN Secretary-General Antonio Guterres, the UN Security Council president, International Maritime Organization chief Arsenio Dominguez, and the president of the International Committee of the Red Cross.

Darzi said the Naji-15 and Naji-16 were struck in the early hours of Thursday off the coast of Hormozgan Province while they were engaged “exclusively” in search-and-rescue duties, sustaining significant damage. The diplomat did not mention any casualties.

“The deliberate targeting of vessels exclusively assigned to maritime search-and-rescue operations constitutes a flagrant violation of international humanitarian law and the international law of the sea”, Darzi said, as cited by Press TV.

He added that their “sole mission is to save the lives of persons in distress at sea” regardless of their affiliation, stressing that targeting rescue vessels “amounts to a war crime.” Darzi went on to say that Iranian rescue boats and marine ambulances have been repeatedly targeted since the US-Israeli operation against Iran began on February 28.

In early March, Iranian media reported that US-Israeli strikes hit the only sea ambulance coursing between Hormuz Island and Bandar Abbas, the capital city of Hormozgan Province, though without casualties.

US officials have not responded to the accusation, although US Central Command (CENTCOM) said its forces have been attacking Iranian “maritime capabilities, missile and drone storage facilities” and coastal targets to degrade Iran’s ability to attack civilian and commercial vessels.

Tehran’s accusation comes amid an escalating standoff over the Strait of Hormuz, with the US maintaining the blockade of Iranian ports. Iran has said vessels can pass through the strait if they abide by its regulations.

On Saturday, Axios reported that US President Donald Trump suspended strikes on Iran after nearly two weeks of nightly bombing to give more space for diplomacy. A New York Times report, however, suggested that the halt was caused by concerns that the Pentagon is running low on air defense missiles.