Each side blamed the other for the collapse of the negotiations aimed at halting fighting that has killed thousands and driven up global oil prices over the past six weeks, the Reuters news agency reported.
"The bad news is that we have not reached an agreement, and I think that’s bad news for Iran much more than it’s bad news for the United States of America," US Vice President JD Vance, who led the American delegation, told reporters before leaving Islamabad.
"So we go back to the United States having not come to an agreement," he said. "We've made very clear what our red lines are."
Vance said Iran had refused to accept US terms, including commitments not to develop nuclear weapons.
"We need to see an affirmative commitment that they will not seek a nuclear weapon and will not pursue the tools needed to quickly achieve one," he said.
The talks marked the first direct meeting between US and Iranian officials in more than a decade and the highest-level contacts since Iran’s 1979 Islamic Revolution, according to Reuters.
Washington and Tehran on April 7 agreed to a two-week ceasefire, reaching the deal shortly before a deadline set by US President Donald Trump for Iran to reopen the Strait of Hormuz.
The ceasefire announcement marked a sharp shift from Trump's earlier warning that "a whole civilization" could be wiped out.
The agreement followed mediation efforts by Pakistan’s army chief, Field Marshal Asim Munir, and Prime Minister Shehbaz Sharif, according to reports.
Poland has condemned attempts to escalate the conflict in the Middle East and urged all sides to exercise restraint and respect international law.
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Source: Reuters, IAR, PAP