Pakistan, Iran's eastern neighbour, has been mediating between Tehran and Washington in an effort to end the conflict, which broke out on February 28 when the US and Israel launched attacks.

"Munir has left today for an official visit where he will have meetings with Iranian leadership," the sources in Pakistan said.

Iranian media had reported on Thursday that Munir had been due in Tehran that day in order to continue "talks and consultations" with Iranian authorities.

Munir's visit comes after Pakistan's Interior Minister Mohsin Naqvi travelled to Iran on Wednesday and met President Masoud Pezeshkian and Foreign Minister Abbas Araghchi.

Pakistan hosted in April the only direct negotiations between US and Iranian officials to take place since the war began.

Munir was at the centre of the action during that round of talks, greeting both delegations on their arrival and displaying bonhomie with US Vice President JD Vance.

But the talks ultimately failed, with Iran accusing the US of making "excessive demands".

Since then, the two sides have exchanged multiple proposals, with the threat of renewed war looming all along.

A ceasefire agreement since April 8 has halted hostilities but US President Donald Trump warned on Wednesday that the window for diplomacy was closing.