President Donald Trump has suggested talks aimed at ending the war in Iran could resume this week, after negotiations collapsed at the weekend, prompting the US to blockade Iranian ports.

"You should stay there [Islamabad], really, because something could be happening over the next two days, and we're more inclined to go there," Trump was quoted as saying in an interview with the New York Post.

His remarks came as the American military said no ships had passed through the US-enforced blockade of Iranian ports and coastal areas in the first 24 hours of the operation.

The stand-off has raised doubts over the prospects for a two-week ceasefire that is due to expire next week.

The Iranian side has not yet responded to Trump's remarks, but United Nations Secretary General António Guterres said it was "highly probable" that talks would restart.

Gulf, Pakistani and Iranian officials also said negotiating teams from Washington and Tehran could return to Pakistan later this week, with no date yet agreed, Reuters news agency reports.

Hopes that diplomacy might continue helped soothe oil markets, pushing benchmark prices below $100 on Tuesday.

Iran has effectively shut the Strait of Hormuz, a crucial global waterway for oil and gas transport, since it came under attack from US and Israeli air strikes on 28 February.

More than a dozen US warships and some 10,000 US military personnel are now enforcing the blockade against vessels of any country entering or leaving Iranian ports, starving Iran of a vital economic lifeline.

It is aimed at putting pressure on Tehran by targeting two of the country's major sources of revenue: oil revenue and the significant tolls Iran demanded from ships for passage through the critical waterway.

US Central Command (Centcom), which is responsible for US military activity in the Middle East and parts of Central Asia, said six merchant vessels had "complied with direction" from American forces to turn around and return to Iranian ports within the first 24 hours of the blockade.

Ship-tracking data analysed by BBC Verify showed that at least four Iran-linked shipping vessels had crossed the Strait of Hormuz despite the blockade. At least two of the ships had previously been at Iranian ports.

A further three ships that were not linked to Iran were seen to have crossed the strait after the blockade started on Monday, BBC Verify says.

Initial high-level negotiations in the Pakistani capital of Islamabad over the weekend failed to produce a deal, with the US saying Iran hadn't agreed to its terms.

Iran's nuclear ambitions were a key sticking point.

The US had proposed a 20-year suspension of all uranium enrichment by Iran, a US official told the BBC's US partner CBS News.

But Tehran had suggested a five-year halt, sources told other US media.

As the International Monetary Fund (IMF) warned the war could plunge the global economy into recession, US Treasury Secretary Scott Bessent told the BBC that a "small bit of economic pain" is worthwhile for long-term international security.

On Tuesday, however, China described the blockade as "dangerous and irresponsible" and warned that it would only "exacerbate tensions and undermine the already fragile ceasefire agreement".

Meanwhile, Israel and Lebanon have agreed to launch direct negotiations after talks in Washington on Tuesday, stemming from Israeli airstrikes on its northern neighbour targeting the Iran-backed militant group Hezbollah.

The meeting at the US state department marked the first direct talks between the two countries' officials since 1993 and were described as "'productive" by the Lebanese ambassador to the US and as opening a path to a "new era of peace" by the Israeli ambassador.

A US official stressed to the BBC that there was no link between the US-Iran negotiations in Islamabad and the Israel-Lebanon talks in Washington.