Iran is still reviewing a US proposal to end the war in the Gulf, despite an initial response that was negative, a senior Iranian official told Reuters, indicating that Tehran had so far stopped short of rejecting it outright.
Publicly, Iranian officials poured withering scorn on the prospect of any negotiations with the administration of US President Donald Trump.
But an apparent delay in delivering a formal response to Pakistan, which delivered a 15-point proposal on behalf of Washington, appeared to signal that at least some figures in Tehran may be considering it.
The senior Iranian official's comments that the proposal was still under review - though the initial response was "not positive" - appeared to contradict a report by Iran's Press TV that cited an unidentified official as saying Iran had rejected it.
A senior Pakistani security official said that Pakistan had followed up with Iran's foreign minister and was still awaiting a formal reply.
A second Pakistani source said: "The Iranians told us they will get back to us tonight. The media is reporting they've said no. But we have not received any official confirmation from Iran. So we are just waiting. They are all underground and communication is a big challenge."
Another senior Iranian official had earlier confirmed that Tehran had received a proposal and said that talks, if they went ahead, could be held in either Pakistan or Turkey.
Pentagon to send more troops
Oil prices fell and shares regained some ground today after reports that Washington had sent the 15-point plan to Iran, with investors hoping for an end to a war that has killed thousands of people and disrupted global energy supplies.
The senior Pakistani security official said Pakistani intelligence had delivered the US proposal to Iran, and Foreign Minister Ishaq Dar had followed up with Iranian Foreign Minister Abbas Araqchi.
So far there had been no response from the Iranians, or any confirmed dates or venue for talks, the Pakistani official said.
Three Israeli cabinet sources said Prime Minister Benjamin Netanyahu's security cabinet had been briefed on the US proposal.
They said its terms included removing Iran's stocks of highly enriched uranium, halting enrichment, curbing its ballistic missile programme and ending funding for regional allies.
The Pentagon is meanwhile planning to send thousands of airborne troops to the Gulf to give Mr 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.
Iranian military rules out deal with Trump
Pakistan has offered to host talks attended by senior US officials as soon as this week.
A senior ruling party official in Turkey, Harun Armagan, told Reuters that Ankara was also "playing a role passing messages" between Iran and the US.
But so far there has been no public recognition from Iran that it is willing to negotiate at all, and its assertions that it will not do so have become increasingly caustic.
"Has the level of your inner struggle reached the stage of you negotiating with yourself?" the top spokesperson for Iran's joint military command, Ebrahim Zolfaqari, taunted Mr Trump in comments on Iranian state TV.
"People like us can never get along with people like you," he said. "As we have always said ... no one like us will make a deal with you. Not now. Not ever."
Iran's foreign ministry spokesperson, Esmail Beghaei, appearing on television in India, said nuclear talks had already been under way when Mr Trump attacked.
He called this "a betrayal of diplomacy" that proved further talks were pointless.
There are "no talks or negotiations between Iran and the United States", he said. "No one can trust United States diplomacy."
A senior Israeli defence official said Israel was sceptical Iran would agree to the terms, and that Israel was concerned that US negotiators might make concessions in any talks.
Trump's softer stance soothes markets
A source familiar with Israel's war plans said Israel wanted any US-Iranian agreement to preserve Israel's option to conduct pre-emptive strikes.
Mr Trump said early in the war that it would end only with Tehran's "unconditional surrender", but has abruptly changed tack this week, saying "productive" talks were already under way with unspecified Iranian officials.
His softer stance has brought a respite in financial markets, which have see-sawed but largely stabilised since Monday when he postponed a threat to escalate the bombing by attacking Iran's civilian energy system.
Iran has derided Mr Trump's announcement as an attempt to buy time and placate markets.
More strikes
The war has raged on with no let-up in air attacks against Iran, or in Iranian drone and missile strikes against Israel and US allies.
An Israeli military official, asked whether Israel had adjusted its military plans since Mr Trump said talks were under way, said it was "pretty much business as usual".
The Israeli military described several new waves of attacks on Iran during the day, including one on Iran's construction of ships and submarines.
The semi-official Iranian SNN News Agency said a residential area was hit in Tehran, with rescuers searching the rubble.
Kuwait and Saudi Arabia said they had repelled new drone attacks.
Iran's Revolutionary Guards said they had launched new attacks against Israel and US bases in Kuwait, Jordan and Bahrain.
Since the start of what the US calls "Operation Epic Fury", Iran has attacked countries that host US bases and effectively closed the Strait of Hormuz, conduit for a fifth of the world's oil and liquefied natural gas.
Iran has told the United Nations Security Council and the International Maritime Organization that "non-hostile vessels" may transit the strait if they coordinate with Iranian authorities.
In practice, however, only Iran's own oil and a handful of ships from friendly countries have made it through.
