All 65 passengers and crew are feared dead in a plane crash after the domestic flight disappeared during bad weather in a mountainous region of central Iran.

A spokesman for Iranian carrier Aseman Airlines told state television on Sunday night that all the passengers were killed.

The airline issued a statement Monday morning (AEDT) saying it could not reach the crash site and therefore could not “accurately and definitely confirm” everyone had died.

The airline also initially said 60 passengers and six crew were on board the French-built, twin-engined turboprop ATR 72 that was flying to the southwestern city of Yasuj.

It later said there were a total of 65 people on board, after one passenger missed the flight.

The 25-year-old plane is believed to have crashed near the town of Semirom after taking off from Tehran’s Mehrabad airport, emergency services spokesman Mojtaba Khaledi told the ISNA news agency.

“Given the special circumstances of the region, we still have no access to the spot of the crash and therefore we cannot accurately and definitely confirm the death of all passengers of this plane,” Aseman said in a statement.

As night approached, bad weather prevented helicopters searching the probable crash site, but emergency workers were scouring the mountainous area by land, local media reports said.

“It is getting colder and darker, and still no sign of the plane,” said a television reporter accompanying rescue teams searching snow-covered areas in Mount Dena, which has more than 40 peaks higher than 4000 metres.

Media reports said the plane disappeared from radar screens 50 minutes after taking off from Mehrabad airport which mainly handles domestic flights.

A man identified himself to the local Tabnak news website as the passenger who missed the flight.

Showing an unused ticket as proof, he said: “God has been really kind to me but I am so sad from the bottom of my heart for all those dear ones who lost their lives.”

The passengers’ relatives have gathered at a mosque near Mehrabad airport, according to Reuters news agency.

“I kept telephoning all morning but they (the relative) wouldn’t answer. So I called my brother and he said they will get here, it (the plane) is not behind schedule yet,” a young woman told a reporter for state television.

“I told him it is raining here. He said no (meaning, don’t worry). He called later and said the plane had crashed.”

Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani issued messages of condolences.

The President asked the transport minister to lead an investigation into the crash.

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Iran’s ageing aircraft fleet has suffered several accidents in recent years.

The country struggled to obtain spare parts to maintain its planes in the face of international sanctions imposed to curb its nuclear programme.

Most of the sanctions were lifted under a 2015 deal between Iran and the US, alongside several other powers.

– With AAP