Thirty-eight people, mostly patients, were killed on Friday in a fire that ravaged a hospital in the Moscow region, with the victims engulfed by flames as they slept behind barred windows.

The deadly nighttime blaze raised new questions about security standards at Russia's medical institutions, in particular psychiatric hospitals, after a string of fires in recent years.

Ministry for Emergency Situations workers and fire fighters examine the site of a fire at a Moscow psychiatric hospital on Friday morning, which killed 38 people, including two nurses. Pavel Sergeyev / Associated Press

The one-story brick-and-wood hospital building housed patients with severe mental disorders, Health Ministry officials said. An Emergencies Ministry official said the fire started in a wooden annex and then spread rapidly to the main brick building, which had wooden beams.

The hospital was in the small town of Ramensky around 100 km outside Moscow as the patients slept heavily after being given sleeping pills.

Officials said the residents of the wing of Hospital No14 were burnt to death or suffocated as the fire spread rapidly through the building, although three managed to escape in the early stages of the inferno.

"According to preliminary information, 38 people died, three survived - one staff medic and two patients," the health ministry said in a statement.

The emergency situations ministry listed those believed to have died as two female orderlies and 36 patients, said the ministry spokeswoman for regional investigators, Irina Gumyonnaya.

The ministry said later that 38 bodies had been recovered, all of them still in beds, including staff.

The ministry said the first report of the fire was at 2 am local time and the blaze was localized two hours later. However it took the fire services over an hour to reach the site, instead of the standard 20 minutes.

Acting Moscow region governor Andrei Vorobyov told Rossiya 24 television that "the investigation must decide whether the (window) bars were the reason or not" for why so few were able to flee to safety.

The patients slept soundly as they had taken medication in the evening, the ITAR-TASS news agency reported, citing a spokesman for the rescue operation.

The smoke alarms did activate in the hospital and woke a nurse who managed to save two patients, the rescue operation spokesman said.

"When the nurse came out into the corridor, the fire was burning and the flames were spreading quickly. She managed to bring out only two patients, a woman and a young man," the spokesman said.

Russia's Investigative Committee said in a statement it had opened a criminal probe into a failure to observe fire security regulations, causing multiple deaths.

They were considering a short circuit or dangerous handling of fire as possible causes. The investigators said the fire was believed to have started in a sofa in a recreation room.

One of the two patients to survive gave evidence that a recently admitted drug addict was going through withdrawal and constantly breaching a smoking ban, investigators said.

"I think the fire started because one of the patients used to often enjoy cigarettes," surviving patient Dmitry Gladkikh, told the Life News website.

According to the list released by the emergency situations ministry, the ages of the victims varied widely with several patients in their 70s but others only in their 20s.

The youngest victim appeared to be a female patient named Lyubov born in 1993.

The institution's chief doctor, who was not named by Russian media, described the patients as a "very tough group of people - psychiatric patients with chronic illnesses and frequent attacks" who suffered from alcohol and drug addiction.

The fire was the latest tragedy to hit a medical institution in Russia, which still suffers from outdated infrastructure and lax security procedures.

In 2006, a fire in a Moscow drug rehabilitation clinic killed 45 women many of whom were trapped by metal bars on the windows that staff could not open.

Russian Health Minister Veronika Skvortsova ordered a check of all the country's psychiatric hospitals by the end of next month.

AFP-AP