Iran says the US has committed a "gross violation" of the ceasefire with new air strikes it launched on the country in the past 48 hours.

The US Central Command (Centcom) said Iranian missile sites and boats attempting to place mines had been targeted with what it called "self-defence strikes" in southern Iran on Monday.

Iran's foreign ministry said it held the US responsible for the consequences of its "aggressive and unjustified actions" in the Hormozgan region, which has a coast along the Strait of Hormuz - the crucial waterway Iran has blocked causing a spike in world energy prices.

It is unclear what impact the strikes will have on talks aimed to end the conflict.

"Without a doubt, the Islamic Republic of Iran will not leave any evil unanswered and will not hesitate to defend the Iranian nation," the Iranian statement said.

However, US Secretary of State Marco Rubio said a deal from the talks was still possible, but it would "take a few days".

One of the stumbling blocks reportedly centres on Tehran's request for the release of frozen Iranian funds held abroad.

The talks have been mainly mediated by Pakistan.

However, Iranian negotiators have been taking parts in Qatar this week.

An official briefed on the Doha visit told Reuters news agency that Iran's central bank governor had attended Monday's talks to discuss the frozen assets, with discussions focusing primarily on Iran's stockpile of highly enriched uranium, and the Strait of Hormuz.

Iran has effectively blocked the vital shipping lane, through which around one fifth of the world's oil passes, since the US and Israel started the conflict on February 28.

US, Israel and many Western countries have accused Iran of enriching uranium in order to make a nuclear weapon. Iran says the programme is for peaceful purposes only.