Iran demands the release of $12 billion in frozen assets in a potential deal with the US and insists that another $12 billion "should be transferred within 60 days" of signing the agreement, the semi-official Tasnim news agency reported Tuesday.

Iran’s top negotiator and parliament speaker Mohammed Bagher Qalibaf visited Qatar on Monday for talks aimed at "securing access to $12 billion in the first phase, as well as removing obstacles," Tasnim said, citing a source familiar with the matter.

"Given past experiences regarding the release of Iranian funds in South Korea and Qatar, emphasis was placed on carefully monitoring the implementation process to avoid repeating previous issues," the source said.

The source noted that Qalibaf’s visit aimed to ensure smooth access to the funds.

The negotiations in Qatar were "generally positive and contributed to progress in broader negotiations," he added.

Regional tensions have escalated since the US and Israel launched strikes against Iran in February. Tehran retaliated with strikes targeting Israel as well as US allies in the Gulf, along with the closure of the Strait of Hormuz.

A ceasefire took effect on April 8 through Pakistani mediation and was later extended by US President Donald Trump indefinitely.

On Saturday, Trump said an agreement with Iran to end the conflict had been “largely negotiated” and was awaiting finalization. (AA)