An Iranian passenger plane skidded off the runway and smashed its wing on the ground, sparking a fire as it landed in the northeastern city of Mashhad on Friday, killing 29 people, Iran's aviation chief said.

His comments corrected an earlier report of 80 dead, which had come from state-run television.

The plane, carrying 148 people, slid off the runway, "then its left wing hit the ground and caught fire," Nourollah Rezai Niaraki, chairman of Iran's Civil Aviation Organization, said in an interview on the television.

Niaraki said it was not immediately known why the plane skidded off the runway. Earlier, the television said a tire on the aircraft exploded while landing, but that could not be confirmed.

Rescue workers carried survivors on stretchers out of the gutted craft, which lay in a pool of water near the runway. In footage shown on the Iranian television, the middle section of the plane was charred and the roof collapsed, while firefighters sprayed the engines with water.

The flight -- by Iran Airtour, which is affiliated to Iran's national air carrier -- originated in Bandar Abbas, in the south of the country. The television said none of the flight's crew were among the dead.

CountryWatch: Iran

The craft was a Russian-madeTupolev Tu-154, the same make as a passenger jet owned by Russia's Pulkovo Airlines that crashed in Ukraine on Aug. 22 while en route from a Russian resort to St. Petersburg, killing all 170 people on board.

In 2002, a Russian-made Tupolev-154 crashed in the mountains of western Iran, killing all 119 people on board.

Mashhad, located 620 miles northeast of Tehran, is visited by some 12 million people annually on pilgrimage to its Shiite Islamic shrines. It was not clear, however, if the passengers in Friday's flight included pilgrims.

Iran has frequent plane accidents and has several times blamed them on U.S. sanctions that it says make it difficult to import spare parts, even from Europe. However, it does not have similar difficulty buying parts for its Russian planes, some of whose recent crashes have been blamed on poor maintenance and other problems.

The West offered to open the door to sales of new planes and spare parts in an incentive package aimed at getting it to roll back its nuclear program.

The Tu-154, the workhorse of passenger airlines in the former Soviet Union, has been in commercial service since 1972. More than 900 have been built and more than 160 exported to airlines around the world. Due to noise and pollution regulations, the planes do not fly to Western destinations.

Iran Air has seven Russian-made Tupolevs among its 43-plane fleet. It also has seven are Boeings that were bought before the 1979 Islamic revolution, as well as 28 European Airbus and Fokker planes.

Six people died in a cargo helicopter crash in August just north of the capital, Tehran.

In March, Iran Air expressed interest in purchasing U.S. aircraft although it wasn't clear how it would circumvent U.S. sanctions in place since 1979 when diplomatic relations were cut after militants stormed the U.S. embassy and held hostages for more than a year.