Iranian soldiers take part in the "National Persian Gulf day" in the Strait of Hormuz, on April 30, 2019.



Iran's elite Revolutionary Guards rejected on Thursday a U.S. claim that they tried to stop a British tanker in the Gulf a day earlier, the Guards said in a statement carried by the semi-official Fars news agency.

Five boats believed to belong to the Guards approached a British oil tanker in the Gulf on Wednesday and asked it to stop in Iranian waters close by but withdrew after a British warship warned them, U.S. officials said.

The Guards' Navy said in a statement their patrol boats were carrying out normal duties, according to Fars.

"In the past 24 hours there has been no encounter with foreign ships including English ships," the statement said.

However, the British government said on Thursday three Iranian vessels had tried to block the passage of the British Heritage through the Straits of Hormuz but backed off after receiving a warning.

"HMS Montrose was forced to position herself between the Iranian vessels and British Heritage and issue verbal warnings to the Iranian vessels, which then turned away," a British government representative said in a statement.

Tensions between Iran and the United States and its allies have risen sharply since Washington stepped up economic sanctions against Iran and moved to bring its oil exports to zero as part of a "maximum pressure" policy to make Iran halt actions that it said undermined regional security.

British Royal Marines boarded an Iranian tanker, Grace 1, off Gibraltar last week and seized it on suspicion that it was breaking sanctions by taking oil to Syria.