The United Arab Emirates has come under attack from Iranian missiles and drones for the second day in a row, according to its Defence Ministry, while Iran denied being behind the aggression.

Iran’s Islamic Revolutionary Guards Corps (IRGC) said late on Tuesday that the country’s forces “have not carried out any missile or drone operations against the UAE in recent days”.

US President Donald Trump later put the number at seven boats.

The US operation, dubbed “Project Freedom”, has shaken a fragile ceasefire reached between Iran and the US on April 8, and renewed fears of a return to war.

Iran’s state broadcaster IRIB quoted an unnamed Iranian military commander as saying that Tehran launched an investigation following the US claim of attacks on IRGC vessels.

It said that while none of the IRGC vessels was hit, the investigation found that US forces had “attacked two small boats carrying people on their way from Khasab on the coast of Oman to the coast of Iran on Monday”.

The attacks destroyed the boats and killed five civilian passengers, the commander said. The US “must be held accountable for their crime”, he added.

There was no immediate comment from the US military.