Iran warns of 'faster, heavier, more painful response' to US attacks

Iran's top negotiator has warned of "a faster, heavier, and more painful response" to US attacks, as hostilities between the two sides escalate.

Parliament speaker Mohammad Bagher Ghalibaf said on Sunday that Americans must understand "before it is too late" that the "rules of the game have changed", according to a translation of his comments on state media.

His comments come nearly a week into renewed fighting between Iran and the US, and a day after Washington said it struck Iranian oil tankers in response to Tehran attacking American warships in the region's waters.

The BBC has contacted US Central Command (Centcom) for comment.

Iranian state media also reported on Sunday that the country's Navy had attacked an American remote-controlled vessel that was trying to enter the Strait of Hormuz.

"The report came from Iranian state media and it's a total lie," said Captain Tim Hawkins, a spokesperson for Centcom, according to the Associated Press.

US Defence Secretary Pete Hegseth has issued his own threats back at Iran, writing on social media on Saturday, "It's simple: if Iran shoots at US ships, we will destroy (and sink) their oil tankers."

A 60-day ceasefire between the US and Iran formally expired last month, and that period of relative calm was shattered when the US resumed attacks last Sunday.