A large fire has broken out at the key oil port of Fujairah in the United Arab Emirates (UAE) after it was hit by a drone attack from Iran, local officials say.

Three Indian nationals were injured in the strike, officials said.

It came after the UAE defence ministry said it had intercepted three missiles launched from Iran, with a fourth falling into the sea. Its foreign ministry earlier reported a tanker affiliated with Adnoc, its state-owned oil company, was hit in the Strait of Hormuz.

The UAE called the attacks a "dangerous escalation". Iranian state TV has quoted an unnamed military official as saying that Iran had "no plans to target the UAE".

The rising tensions come as the US said navy destroyers and US-flagged merchant ships sailed through the Strait of Hormuz on Monday.

Iran called the claims "entirely false" and its military said it fired warning shots at a US warship. Washington earlier denied a claim in Iranian state media that Iranian missiles had hit a US ship. Later on Monday Donald Trump said the US had "shot down" seven Iranian fast boats in the strait. Iran denied that this had happened.

The Strait of Hormuz has remained largely blocked since the US and Israel launched air strikes on Iran in February and Tehran responded by blocking the crucial waterway through which 20% of the world's oil and liquefied natural gas is meant to pass freely.

In early April the US and Iran announced a ceasefire under which Iran ended its drone and missile strikes on Gulf countries including the UAE, but few vessels have been able to transit the strait since then and the US imposed its own blockade on Iranian ports.

The benchmark Brent crude oil price passed $115 a barrel shortly after the reports that Fujairah had come under attack, up more than 5% on the day.

Fujairah lies on the east coast of the UAE, beyond the Strait of Hormuz. A pipeline from the oilfields of Abu Dhabi runs to Fujairah, allowing limited amounts of crude to be loaded on to tankers and shipped to world markets despite the strait being effectively blockaded.

Earlier on Monday South Korea also reported an explosion on one of its ships anchored just off the UAE.

Neighbouring Qatar condemned the attack on the tanker affiliated with Adnoc and called for the strait's "unconditional reopening".

In Oman, two people were injured when a residential building was targeted in Bukha, along the coastline of the Strait of Hormuz, state media reported on Monday.

On Sunday, Trump said the US would start helping stranded vessels out of the shipping lane. An estimated 20,000 seafarers on 2,000 ships have been stuck since the US-Iran war began in February.

The president said the US had been asked by countries "from all over the World" to help free up their ships which were "locked up in the Strait of Hormuz" and were "merely neutral and innocent bystanders!".

And so, in response, the US would "guide their Ships safely out of these restricted Waterways".

There has been growing concern over dwindling supplies and the effects on sailors' physical and mental health.

But Trump did not say how they would be able to sail away - he only threatened to use force "if, in any way, this Humanitarian process is interfered with".