STPETERSBURG, Russia - A Russian passenger jet crashed in heavy fog and burst into flames on a highway in northwestern Russia, killing 44 people, officials said. Eight people survived.

The Tu-134 plane, belonging to the RusAir airline, had taken off from Moscow and was moments from landing at the airport of Petrozavodsk when it slammed into the highway just before midnight on Monday, said Emergencies Ministry spokeswoman Oksana Semyonova.

The ministry said in a statement on its website that 44 people were killed, including four with dual US and Russian citizenship.

Semyonova said the plane slammed into the ground about 100 meters from a small village, but no casualties were reported on the ground.

Petrozavodsk is in Karelia, near the Finnish border, about 640 kilometers northwest of Moscow.

Russia's top investigative agency said bad weather, human error or a technical malfunction might have contributed to the crash.

A 9-year-old boy and his teenage sister were among eight people who survived the crash, the ministry said.

Anton Terekhin and his 14-year-old sister Anastasia Terekhina are being treated for severe injuries in hospital in Petrozavodsk.

The brother and sister feature on a list of survivors published by the Karelia branch of the emergencies ministry on its website. They are registered as residents of the Pacific island of Sakhalin.

A spokeswoman confirmed that the two were in hospital but that their mother Oksana was killed in the crash. A stewardess, named as Yulia Skvortsova, 23, also survived, the only one of the plane's crew who was not killed.

"The condition of the boy is very serious, critical," said Russian Health Minister Tatyana Golikova. "He has lost a lot of blood," she added, quoted by the ITAR-TASS news agency.

Golikova said that six of the eight survivors would be moved for further treatment in Moscow but that Anton Terekhin's condition was too serious for the authorities to consider moving him to another place.

"Our specialists in Petrozavodsk are preparing the injured for evacuation to Moscow," she said.

Adding to the difficulty of landing the plane in deep fog, the runway's high-intensity illumination intended to help the crew at times of low visibility failed just as the plane was on its final approach, said Alexei Morozov, deputy head of the Interstate Aviation Committee, according to the ITAR-TASS news agency.

The airport's chief, Alexei Kuzmitsky told the Interfax news agency that according to preliminary information provided to the authority, the descending plane clipped a power line, cutting off the runway lights.

Sergei Shmatkov, an Russian air traffic controller who oversaw the plane's approach, was quoted by the lifenews.ru online newspaper as saying the visibility near the airport was close to the minimum admissible level at the time of the crash, but the pilot still decided to land.

"Most likely, the crew continued descent at a moment when they already should have begun a second run," he told the lifenews.ru in a telephone interview.

Shmatkov said he ordered the crew to abort the landing the moment the runway lights went off, but it was already too late.

RusAir said the plane was in good working order.

The Tu-134, along with its larger sibling the Tu-154, has been the workhorse of Soviet and Russian civil aviation since the 1960s. The model that crashed was built in 1980, had a capacity of 68 people and a range of about 2,000 km.

AP-AFP