At least 168 passengers and crew are feared dead after a Caspian Airlines plane crashed in the north of Iran, state media says. Wreckage was spread over a large area in a field in Jannatabad village, Qazvin province, about 75 miles (120km) north-west of Tehran, state TV said. The Tupolev aircraft was flying from the Iranian capital to Yerevan in Armenia, Iranian media said. The cause of the crash, which happened soon after take-off, was not known. "The 7908 Caspian flight crashed 16 minutes after its take-off from the International Imam Khomeini Airport," Iran's Aviation Organisation spokesman, Reza Jafarzadeh, was quoted by Iranian Press TV as saying. An eyewitness said the plane dropped out of the sky and exploded on impact. Television footage showed a massive crater in a field, with smouldering debris over a wide area. Mr Jafarzadeh said there were no irregularities reported before the plane took off. "The regulations of the State Aviation Organisation do not allow a plane to take off before security of the plane is 100% approved," he told Iranian television. "As to why this happened and what problem the plane ran into, we will need to carry out a thorough investigation of all contributing elements." The plane was built in Russia in 1987. A Caspian Airlines representative told Associated Press news agency that most of the passengers were Armenians, with some Georgian citizens also on board. It was unclear if other nationalities were involved. The BBC's Jon Leyne said the country was reliant on air transport, but it had been three years since the last crash. The civil and military fleets are made up of elderly aircraft, in poor condition due to their age and lack of maintenance. Since Iran's Islamic revolution of 1979, trade embargoes by Western nations have forced Iran to buy mainly Russian-built planes to supplement an existing fleet of Boeings and other American and European models. Source: BBC