Iran in 'serious discussions' with US, Trump says, as military threat looms

President Trump has confirmed Iran is in "serious discussions" with the US following the steady build-up of American military forces in the Gulf.

The US president said he hoped negotiations with Iran would lead to something "acceptable", as tensions between the two countries remain high.

Iran's top security official Ali Larijani also said a framework for negotiations was progressing.

Trump has threatened to intervene in Iran over its nuclear ambitions and after its deadly crackdown on anti-government protests. Iran has said it would respond "immediately and powerfully respond" to any aggression by land or sea.

Around a fifth of the world's traded oil passes through the waterway, which is about 33km (21 miles) wide at its narrowest point between Iran and Oman. Iran has in the past threatened to close the waterway in the event of an attack on it.

The US has warned Iran against any "unsafe and unprofessional behaviour" near its forces in the area.

Iran's Foreign Minister Abbas Araghchi responded by saying: "The US military is now attempting to dictate how our Powerful Armed Forces should conduct target practice in their own turf."

As part of its build up of forces the US has sent its aircraft carrier USS Abraham Lincoln to the region and late last week US central command said it was operating in the Arabian Sea.

On Saturday two explosions in Iran heightened anxiety in the country. Local authorities said a blast that killed one and hurt 14 at a building in the southern port city of Bandar Abbas was caused by a gas leak.

The semi-official Tasnim news agency denied social media reports that a Revolutionary Guards Corps navy commander had been targeted in the blast.

In the south-western city of Ahvaz, at least four people were killed in another explosion, with local authorities again blaming a gas leak, according to Iran's Tehran Times.

On Thursday, Trump said he had told Iran that it had to do two things to avoid US military action: "Number one, no nuclear. And number two, stop killing protesters."

The US-based Human Rights Activists News Agency says it has confirmed the killing of more than 6,300 people since the unrest began in late December, and is investigating another 17,000 reported deaths.

Another group, the Norway-based Iran Human Rights (IHR), has warned the final toll could exceed 25,000.