Iran and the US continue to have "fundamental" disagreements over Tehran's nuclear programme, a senior Iranian official said on Thursday, as Pakistan intensifies efforts to broker a peace deal before the fragile two-week ceasefire ends next week.
A Pakistani delegation led by the country's powerful military chief travelled to Tehran on Wednesday to arrange a second round of negotiations after initial talks in Islamabad over the weekend failed to produce an agreement.
"The trip of the Pakistani army chief to Tehran was effective in reducing differences in some areas, but fundamental disagreements still remain in the nuclear field.... More hopes have been created for extending the ceasefire and holding a second round of talks," the Iranian official told Reuters .
"The fate of Iran’s highly enriched uranium and the duration of Iran’s nuclear restrictions are among the highly disputed issues for which no solution has yet been found."
Pakistan is leading international efforts to broker a long-term agreement between the two sides and prevent a return to a conflict that has caused widespread destruction across the region and triggered a global energy crisis.
US President Donald Trump has struck a positive tone on the negotiations this week, suggesting that talks could resume in Islamabad within days.
"We feel very good about the prospects of a deal," White House press secretary Karoline Leavitt told reporters on Wednesday, adding that talks would "very likely" continue in Pakistan's capital.
Trump also indicated on Tuesday that US negotiators could return to Pakistan before the end of the week.
But Pakistan's foreign ministry on Thursday said there had been no agreement between the two countries over the time and date of the proposed negotiations.
Despite the diplomatic push, the US is continuing to build up its military presence in the Middle East in a bid to pressure Tehran. US officials said another 6,000 troops will be deployed in the coming days, bringing the total number of personnel in the region to around 50,000.
Marathon talks in Islamabad over the weekend failed to produce a breakthrough and were followed by a US announcement of a blockade on Iranian ports , adding pressure on the ceasefire that came into effect on 8 April.
Pakistani officials are now racing to arrange fresh negotiations before the truce expires on 22 April.
Field Marshal Asim Munir led the delegation to Tehran, where they reportedly delivered a US message and sought to arrange a second round of talks.
Pakistan’s Prime Minister Shehbaz Sharif is visiting Saudi Arabia, Qatar and Turkey this week in a bid to build momentum for renewed negotiations.
Speculation over a second round of talks has grown since the weekend, when 21 hours of discussions failed to yield an agreement. US Vice President JD Vance identified the nuclear issue as a key sticking point, saying in Islamabad that Tehran had not provided guarantees it would not pursue a nuclear weapon.
The future status of the Strait of Hormuz is also seen as a major obstacle, with Iran continuing to demand control over the strategic waterway as part of any deal. The Islamic Revolutionary Guard Corps took control of the strait after the war began at the end of February and has since imposed fees on the limited number of ships leaving Gulf waters.
The effective closure of the strait, which previously carried around a fifth of the world’s oil and gas, has triggered a global energy crisis.
The US responded to the breakdown in talks by imposing a blockade on Iranian ports, allowing only vessels not linked to Iran to leave the region. The move is expected to increase pressure on global energy markets and has raised tensions with China, the largest buyer of Iranian oil.