TEHRAN - Some 42 Iranians were injured when a Russian-made Tupolev aircraft caught fire as it landed in northeastern Iran on Sunday, state radio said.

About 42 passengers, out of 157 aboard, were injured when the plane was landing at Mashhad city's airport, said Gholamreza Massoumi, head of Iran's emergency medical services.

There were no fatalities, said Iran's civil aviation spokesman Reza Jafarzadeh.

A senior local official said the wounded were not in a critical condition, state television said.

The official IRNA news agency said the incident occurred when the rear end of the plane, which belonged to Iran's domestic Taban Airliner, caught fire while landing.

Mashhad is a popular destination for pilgrims among Iran's majority Shi'ite Muslims.

The cause of the incident was being investigated, IRNA said.

Russia's Federal Air Transport Agency said on Sunday it will investigate the reasons behind the fire and said weather conditions and visibility problems were most likely behind the incident, state-run news agency RIA-Novosti reported.

The airplane touched the ground with a large load, resulting in part of the runway being damaged, it said.

In the worst plane crash in Iran in the past six years, a Tupolev aircraft crashed in 2009 in Iran on its way to Armenia, after catching fire mid-air and crashing into farmland killing all 168 people on board.

Iran has suffered a string of crashes in the past few decades, many involving Russian-made aircraft.

U.S. sanctions against Iran have prevented it from buying new aircraft or spare parts from the West, forcing it to add to its aging fleet of Boeing and Airbus planes with aircraft from Russia and other former Soviet Union states.

(Additional reporting by Amie Ferris-Rotman in Moscow; Writing by Reza Derakhshi; Editing by Louise Ireland)