Rescue teams are reported to have recovered the bodies of at least 44 people - including many aviation experts - who died when a Ukrainian plane crashed in central Iran.

The Antonov An-140 twin-engine turboprop crashed into a mountainside at about 1930 (1600 GMT) on Monday as it was preparing to land in Isfahan, about 400 kilometres (250 miles) south of the capital Tehran.

Casualty figures vary slightly, but Ukrainian Foreign Ministry spokesman Sergei Borodenkov said there were 38 passengers and six crew on board.

By coincidence, the plane had been taking Ukrainian and Russian aerospace experts to the first official flight of the Iranian version of the An-140 being manufactured in a joint project in Isfahan.

The Russian Foreign Ministry said the victims included six Russian men who were managers and specialists from various companies. All the other victims are believed to be Ukrainian.

"It was an excellent plane and those on board were the best aviation experts that Russia and Ukraine have," said Ukrainian Prime Minister Viktor Yanukovych, according to the Interfax news agency.

Wreckage collected

The plane had taken off from Kharkiv, Ukraine, and made a brief stop at Trabzon in Turkey before flying on to Iran.

However, as it was nearing the airstrip at Iran Aircraft Manufacturing Industries, near Isfahan, witnesses saw the plane hit a mountain, an Iranian official told Reuters news agency.

"The black box of the plane has been found and efforts are under way to collect the wreckage," a local official told Tehran radio.

The radio said the remains of all of the victims had been recovered.

Iran air crashes

22 fatal accidents known with a combined total of 672 deaths Russian-made Tu-154 airliner crashes into mountains in March 2002, killing 117 people 80 die when a military plane crashes in north-east Iran in March 1997 Tu-154 crashes into a military plane near Tehran in February 1993, killing 132

The cause of the crash is unclear. Air traffic controllers said the plane lost contact minutes before it was due to land.

The Ukrainian President, Leonid Kuchma, and Iranian Transport Minister Ahmad Khorram offered condolences to families of the victims.

The Ukrainian parliament began its session on Tuesday with a minute's silence.

The An-140 is a modern twin-turboprop commuter plane which made its maiden flight in 1999 and has rarely been involved in accidents.

Iran is assembling An-140s - renamed the Iran-140 locally - under licence from Ukraine.

"It was the same model plane that we are developing with Ukraine, but I don't think the crash will affect this project," Mr Khorram told Reuters news agency.