Iranian Supreme Leader Ayatollah Mojtaba Khamenei has called for revenge for the death of his father and predecessor Ali Khamenei.

Vengeance was the "will of the nation", he said in a written statement read out on state TV. It was his first public message since his father's funeral ceremonies began this week.

His father was killed in an air strike on 28 February, the first day of the US-Israeli war against Iran.

Many Iranians taking part in funeral ceremonies over the past few days carried placards calling for the killing of US President Donald Trump, who on Saturday warned that any such plans would see the US "decimate and destroy all areas" of Iran in response.

Ali Khamenei was buried in his home city of Mashhad on Friday.

His son has not been seen in public since before the war, and is rumoured to have been disfigured in the strike which killed his father.

But his statement on Saturday was uncompromising.

"We pledge to avenge the blood of the martyred leader and all the martyrs of these two wars from the criminal and disgraced killers," he was quoted as saying.

"The matter depends neither on my personal existence nor on that of other officials. Whether we are present or not, it will come to pass."

The Wall Street Journal and other US media reported this week that Israel had shared intelligence with Washington that Iran had recently devised a plan to assassinate the US president.

However, Trump denied that Tehran had made a fresh plan or that Israel was the source of any intelligence. He told the New York Post in an interview that he had been "No. 1 [on Iran's kill list] for a long time".

The war began with US and Israeli attacks on 28 February, prompting Iran to attack Israel and US targets and allies in the Gulf.

In June, the US and Iran signed a ceasefire agreement, aimed at facilitating talks to end it.

Earlier this week, three commercial tankers were attacked as they tried to cross a US-recommended route through Omani waters. Iran has repeatedly said the only "safe" route is a separate route through its waters.

The incident prompted a series of US strikes in which 17 people were killed and 115 injured, according to Iranian officials. Iran responded with strikes on US allies in the Gulf.

The exchange raised tensions and prompted Trump to declare the ceasefire over.

However, the US leader said talks would continue and mediators have tried to revive the process.

US officials say they have conveyed through mediators the demand that Iran publicly state that the Strait of Hormuz, a vital international shipping route, is open and pledge to stop firing on commercial ships.

According to US media, Iran told American officials the attacks on tankers were a mistake and blamed a rogue internal group.