Direct contact between senior officials from the United States and Iran has broken down, according to reports, amid soaring tensions surrounding the threat of US military strikes in response to Tehran’s crackdown on antigovernment protests.

Communications between Iranian Foreign Minister Abbas Araghchi and US special envoy Steve Witkoff have been suspended, a senior Iranian official told the Reuters news agency on Wednesday.

The report came amid President Donald Trump’s threats to take military action against Iran over the killing of protesters, just months after US forces bombed Iranian nuclear sites during a 12-day war launched by Israel in June.

Tehran has pledged to retaliate against US military bases in the region should it be attacked.

Amid the tensions, some personnel have been advised to leave the US military’s Al Udeid airbase in Qatar, Washington’s largest military base in the Middle East, by Wednesday evening, Reuters reported, citing diplomatic sources.

Chief justice calls for swift punishments

Despite Trump’s escalating warnings over the crackdown, the head of Iran’s judiciary signalled on Wednesday that there would be swift trials and punishments for those detained in the demonstrations.

“If we want to do a job, we should do it now,” Judge Gholamhossein Mohseni-Ejei said in a video shared online by Iranian state television.

“If we want to do something, we have to do it quickly.”

Any delay would reduce the effect of deterrence, he added.

“If it becomes late – two months, three months later – it doesn’t have the same effect.”

The comments appear to signal fast-tracked trials for detainees linked to the protests, as activists warned that hangings of detained protesters could begin soon.

Iran’s Defence Minister Aziz Nasirzadeh also said the country had “many surprises” in store for anyone that attacked it, and warned that countries that provide assistance for strikes against it would be considered ‘legitimate targets”.

“If these threats are turned into action, we will defend the country with full force and until the last drop of blood, and our defence would be painful to them,” Nasirzadeh said at a security meeting, according to Press TV.

Iranian official: No prospect of nuclear progress

Communication lines had previously remained open between Tehran and Washington throughout the unrest in Iran, which began in late December with protests against the cost of living and a plummeting currency, before broadening into wider antigovernment demonstrations.

Iranian Foreign Minister Abbas Araghchi told Al Jazeera earlier this week that Iran was ready to engage in talks with the US over its nuclear programme, “provided that it is without threats or dictates”.

The US, alongside European allies, had been seeking over the past year to revive a diplomatic push regarding Iran’s nuclear programme.

But the Iranian official who spoke to Reuters suggested that the renewed tensions had wiped out any possibility of progress on the nuclear issue.

The US threats undermined diplomatic efforts, he said, adding that any potential meetings between the two officials to find a diplomatic solution to the decades-long nuclear dispute had been cancelled.

He also said Tehran had asked US allies in the region to “prevent Washington from attacking”.

Iranian state television has acknowledged reports of a high death toll during the nationwide protests, quoting the head of the Martyrs Foundation as saying “armed and terrorist groups” are to blame.

More than 100 security personnel have been killed in two weeks of unrest, Iran’s state media report, while opposition activists say the death toll is higher and includes thousands of protesters. Al Jazeera was not able to independently verify these figures.