The US military launched ⁠a ⁠series of “powerful” ​strikes against Iran, it announced on Tuesday night, in response to what ‌it said were “unwarranted, dangerous” Iranian ​attacks on three commercial vessels in the strait ​of ​Hormuz.

In a statement on social media, US Central Command accused Tehran of a “clear violation” of the ceasefire agreement between US and Iran, which was signed last month.

The attacks were designed “to impose heavy costs for targeting and attacking commercial shipping crewed by innocent civilians in an international waterway”, it added.

Qatar has warned Iran it will bear full legal responsibility after three tankers, including a Qatari LNG vessel, were struck within hours in the strait.

All three were hit close to Oman, which had suggested a new shipping corridor close to its coastline – a proposal Iran opposes, as it wants to charge ships to use the waterway.

Iran blamed the US for the incident on Tuesday, saying Washington’s efforts to open up new routes through the strait constituted a breach of the memorandum of understanding the two parties had signed.

Tehran claims the memorandum is specifically worded to leave it, in consultation with Oman, to manage the reopening of the strait with the aim of commercial traffic returning to prewar levels within 30 days.

At a briefing in Tehran, foreign ministry officials insisted Iran had a right to impose fees on all ships using the strait.

“Securing the strait for navigation for safe passage is itself a service,” said the foreign ministry spokesperson, setting terms for the long-term management of the strait that are likely to be rejected by Oman and western shipping interests.

The United Kingdom Maritime Trade Operations centre (UKMTO) said a Qatari tanker, Al Rekayyat, was hit near Limah, Oman, as it tried to travel south out of the strait toward the Gulf of Oman.

In a mayday call, the Al Rakayyat crew were heard sending out a message: “We’re being hit by a drone top of port side near engine room.”

It was the first time a Qatari ship has been struck since the start of the war between the US and Iran on 28 February. Qatar has been acting as a mediator in the talks, but its foreign ministry spokesperson, Majed al-Ansari, called it a “serious and explicit violation” of international law and said Qatar would hold Iran fully responsible for the act of aggression.

Iran’s foreign ministry claimed the memorandum left it alone to manage the reopening the strait, “but the US has been trying somehow to open new routes”.

The spokesperson also rejected a proposal from Oman to build a new authority for the strait modelled on the Malacca and Singapore strait, where fees are charged only for specific navigational services not including security.

“For a long time we have been generous enough not to ask for anything. Providing security is costly, and Iran and Oman have been doing that for a long time. So from now on we’re going to ask for necessary costs when we provide related services, including securing the safe passage,” the spokesperson said.

He added: “When you provide in the English Channel you call it deep sea piloting, for instance, you call it different names, but that’s the same.”

However, deep sea pilotage in busy waterways is regarded as voluntary.

Iran will face criticism that it is demanding ships pay a compulsory fee or risk being attacked – a situation close to a protection scheme. Tehran argues the strait became contested only because of American aggression.

Iran’s foreign ministry also firmly rejected proposals from France and the UK that they start to de-mine and secure the southern route through the strait close to the Oman shore.

The spokesperson said: “When France and others said they were ready to help, we said ‘no thank you’ – this is for Iran to do it and we know how to do it.”

Saudi Arabia condemned Iran’s targeting of the Saudi-flagged tanker Wedyan and the Qatari tanker Al Rekayyat as they transited the strait of Hormuz, saying the attacks threatened international navigation and global energy supplies.

“The kingdom stresses its demand that Iran immediately stop all actions that threaten the security of the region and the safety of international navigation and energy supplies,” the Saudi foreign ministry said in a statement on Tuesday.

The ministry said Saudi Arabia held Iran “fully responsible for these attacks, their damage and all their repercussions”.

Qatar summoned Iran’s deputy ambassador to Qatar to register its protest amid reports the ship’s crew had abandoned the vessel.

Reports that at least three other ships had been attacked in the past 24 hours have not been confirmed.