Hundreds of Iranian activists both in and outside of the country have warned that Ayatollah Ali Khamenei’s “warmongering” regime is leading Iran “towards destruction” by pursuing hostilities with Israel.

In a letter seen by The Telegraph, they wrote: “In a situation where Iran is facing multidimensional economic, political, and social crises, increased tension between Iran and Israel is detrimental.”

Israel has vowed to respond after Iran launched more than 300 drones, rockets and missiles at the country last weekend.

That attack was in turn a response to an Israeli attack on Iran’s consulate in Damascus, which killed a senior member of the Islamic Revolutionary Guard Corps.

While saying they “condemn any aggression on our country’s soil”, the Iranian letter added that “concerns about the outbreak of a widespread war have become prevalent”.

“[We] express serious concern about any action by the Islamic Republic of Iran that would increase the flames of war in the region, suppress people domestically and further securitise the atmosphere,” the letter read.

“The domestic repressive policies of the Islamic Republic on the one hand, and its inefficient and undemocratic foreign policy on the other, are leading the country towards destruction.

“The need for solidarity among democracy advocates in saying no to warmongering has doubled.”

The letter is signed by more than 350 activists, around 40 of whom are currently inside Iran.

Signatories include Mehrangiz Kar, a prominent human rights lawyer, Parvin Ardalan, the journalist and women’s rights activist, Asieh Amini, the activist and founder of an anti-execution campaign and Monireh Baradaran, the former political prisoner.

The campaigners believe the escalation is being used to suppress dissent and distract from Iran’s domestic crises.

One of the signatories said fear of such suppression prevented more prominent activists inside Iran from signing it.

Mansoura Shojaei, a Netherlands-based women rights researcher, said: “We discussed a lot about getting signatures to the letter from inside Iran but now if people inside Iran even talk about peace and defend peace, they will be blamed for supporting Israel.

“The authorities have intensified their crackdown,” she added. “The crackdown targets people who criticise them on social media and also prominent activists, therefore, few prominent activists inside Iran signed it due to security reasons.”

Ms Shojaei said Iran’s strike on Israel had “pushed the region very close to a wider conflict.”

“For the war in Gaza, Israel was somehow isolated by its allies, but the strikes changed the situation,” she said.

She added that Iran “not only failed to achieve any [attack] objectives” but also “inadvertently bolstered support for Israel, a development they did not anticipate nor desire”.

The Iranian strike did not cause any fatalities and very little damage, with most missiles and drones intercepted in part thanks to assistance from the US, the UK, and neighbouring Jordan.

Israel has not specified when or how it will retaliate to the attack.

On Wednesday, Ebrahim Raisi, Iran’s president, once again warned that even the “tiniest invasion” by Israel would lead to a “massive and harsh” response from Tehran.