The death toll of an apartment building explosion in Russia's northern city of Arkhangelsk early Tuesday went up to 22, and many others still remain trapped under the rubble, the Interfax news agency reported. 

First Deputy Chairman of the Emergency Situations Ministry Yuri Vorobyov said the death toll from the blast, thought to have been caused by gas leak, may continue to rise.

The blast erupted at 3:00 am Moscow time (0000 GMT) when about 70 residents in the nine-storey building in Arkhangelsk, 960 kilometers north of Moscow, where sleeping.

A fire broke out after the building collapsed, hampering rescue work.

Police were searching for two men suspected of involvement in the explosion.

Two middle aged men, thought to be homeless, removed gas valves carrying gas into the house, said Natalya Ozhigina, head of the regional Federal Security Service's public relations department.

But she denied a terrorist attack being the cause of the explosion, saying that "the main version is deliberate sabotage of the gas system for certain aims."

Meanwhile, Arkhangelsk prosecutors opened a criminal investigation into the accident on charges of death and damage by negligence.

Neglect of safety precautions has led to frequent gas explosions in Russian apartment buildings and public facilities.

Moscow police are checking attics, basements and other housing facilities in case of gas system malfunctions, according to Ozhigina.

(Xinhua News Agency March 17, 2004)