TEHRAN : The United States and Iran said they reached a deal to end the Middle East war on all fronts including Lebanon, and reopen the vital Strait of Hormuz, but offered little indication on the thorny question of Tehran's nuclear programme.

Washington and Islamabad said the agreement was to be signed on Friday in Switzerland, signalling what would be a major breakthrough to ending months of war that have taken thousands of lives and roiled energy markets.

Few of the details were made public, but US President Donald Trump said the Strait of Hormuz -- a key conduit for global oil supplies -- would reopen after the planned signing of the deal on Friday.

"The Deal with the Islamic Republic of Iran is now complete," US President Donald Trump posted Sunday on social media as he marked his 80th birthday.

"Ships of the World, start your engines. Let the oil flow!"

Soon after, Iran's Deputy Foreign Minister Kazem Gharibabadi said in televised comments that the deal put an "immediate end" to the countries' war and that they would hold talks within two months to seek a "final agreement."

Just hours earlier, Tehran had vowed to retaliate against a strike by Israel against Iranian ally Hezbollah in the suburbs of Beirut which threatened to push back an agreement.

But later in the day, Pakistani Prime Minister Shehbaz Sharif made the announcement: "Both sides have declared the immediate and permanent termination of military operations on all fronts, including in Lebanon."

He added thanks to leaders of Qatar, Saudi Arabia and Turkey for their support in the mediation effort.

- Details remain unclear -

The content of the agreement, which follows weeks of fraught negotiations and periodic threats from Trump of fresh hostilities unless Iran reached a deal, remained unclear.

Iran's Mehr news agency reported that the US would release $12 billion in frozen assets to Iran before the start of negotiations.

It quoted a 14-point "memorandum of understanding" between the two nations, which it said stipulated "the release of 24 billion dollars in frozen Iranian assets during the 60?day negotiation period" that begins after the MoU is signed.

The Trump administration didn't immediately comment on the details of the agreement, which may prove contentious as the US presses its effort to end Tehran's nuclear ambitions and deal with its stockpile of highly enriched uranium -- believed to have been buried by US strikes last year.

In an interview with the New York Times on Sunday, Trump said Washington was still negotiating whether Iran would suspend its enrichment for 20 years.

The US leader hinted that he might settle for a 15-year suspension, but said he did not want to negotiate via the press.

- 'Seize the moment' -

The announcement of the deal was greeted with international relief and hope for an enduring end to the conflict.

UN Secretary-General Antonio Guterres said it was a "critical step" toward resolving the war in the Middle East.

The United Kingdom, France, Germany and Italy said they were prepared to lift sanctions imposed on Iran and will work "with the US, Iran and regional partners to seize this moment, maintain momentum and achieve a long-term diplomatic settlement."

The announcement also brought relief at market opening on Monday. Oil prices plunged more than four percent in Tokyo, and Japan's Nikkei stock index jumped three percent.

The blockade of the Strait of Hormuz has had a worldwide economic impact, from inflated gas prices that have fueled inflation in the US and many other countries and congested supply chains for goods like fertiliser key to food production in areas far beyond the Middle East.

"What we're going to be able to do is drive down the cost of energy, not just now but for the long term, and create a real engine of prosperity in the Middle East," US Vice President JD Vance told Fox News.

He said that he planned to attend the signing of the peace deal, which was slated to take place in Geneva, and that it was possible Trump could also go.

- Israeli strike -

It was a rollercoaster Sunday, with Trump in the morning angrily blaming Israel for delaying its signing with the airstrike on Beirut, which he said had delayed the agreement.

In an expletive-laden phone interview with US news outlet Axios, Trump had fumed about Israeli Prime Minister Benjamin Netanyahu, saying: "I was so pissed off. I let him know."

The last time Israel hit the Beirut suburbs, it sparked one of the strongest jolts yet to a ceasefire that has largely held since April, with Iran firing off a retaliatory missile barrage and Israel responding with strikes.

Tehran has long demanded that any agreement to halt the war must include the parallel conflict in Lebanon, where Israel has been pursuing a campaign against Iran-backed Hezbollah.