Pakistan has delivered a proposal from the United States to Iran, and either Pakistan or Turkey could be venues for discussions to de-escalate the war in the Gulf, a senior Iranian official told Reuters on Wednesday.

The ​comments, on condition of anonymity, were among rare signs that Tehran might consider diplomatic proposals, despite insisting in public that no talks were under way and it would make no deal with ‌the administration of President Donald Trump.

The source, who asked not to be named due to the sensitivity of the matter, did not disclose details of the proposal and whether it was the 15-point US framework proposal to end the war reported by news outlets.

The source also said Turkey was helping to find ways to end the way and "either Turkey or Pakistan are under consideration as the venue for such talks".

"We are trying to broker US-Iran peace talks and have also offered Islamabad as a venue for the purpose. But it will be possible if Iran agrees to sit at the table with America," a top official in the Shehbaz Sharif administration said on the condition of anonymity.

"At the moment, Pakistan is relaying messages between the US and Iran. Islamabad not only handed over the 15-point proposal of the US to Iran but also Tehran's demands to the Trump administration to ink a peace deal," he said.

Meanwhile, the Pentagon is planning to send thousands of airborne troops to the Gulf to give Trump more options to order a ground assault, sources have told Reuters, adding to two contingents of Marines already on ​their way. The first Marine Expeditionary Unit aboard a huge amphibious assault ship could arrive around the end of the month.