The Russian Tu-134 passenger jet, which crashed Tuesday night and killed all 43 people on board, did not suffer an explosion as earlier reports said, an Emergency Situations Ministry official said Thursday, citing preliminary investigation results at the site of the tragedy as saying.

The plane and the other southbound Tu-154 airliner downed almost simultaneously Tuesday night after taking off from Moscow's Domodedovo Airport, killing all 89 people aboard and raising fears of a terrorist attack.

Eyewitnesses said they heard an explosion before the Tu-134 slammed into the ground about 200 km south of Moscow in the Tula region.

However the unnamed official, who was in charge of the regional administrative affairs, said no signs showed that an explosion had hit the jet as the fuselage maintains basically intact after the crash, according to Interfax news agency.

The official said the jet had spiraled down to the ground and did not catch fire, which indicates that the engine had been shut down in the air.

The Tu-154, carrying 46 people, triggered an SOS alert and then disappeared from radar screens moments later. The wreckage of the jet was found in the Rostov region and early indications suggested it exploded in midair.

Federal Security Service spokesmen said an initial study of the wreckage showed no terrorist act was carried out aboard the two planes, and technical failure, low-quality fuel, fueling violations or pilot error may be to blame.

But Prosecutor General Vladimir Ustinov told President Vladimir Putin that terrorism has not been ruled out.

Transport Minister Igor Levitin, who was appointed by Putin to head the investigation commission, confirmed Thursday that all theories are being examined and not a single version has been dismissed so far, Itar-Tass news agency reported.

Fears of terrorist attacks have been high ahead of Sunday's vote in Chechnya for a president to replace Akhmad Kadyrov, who was killed in a bomb blast in May.

Security has been strengthened at all Russia's airports and the Interior Ministry has pledged to reinforce security measures in public places.

Putin called for a national day of mourning on Thursday, and the search operation in Tula has finished but still continues in Rostov.

Source: Xinhua