MOSCOW - Winters in the Russian capital are harsh, persistent and long. For at least 400 people every year, they are also deadly - and with a bitter cold spell refusing to loosen its grip, the international aid group Medecins Sans Frontieres appealed Friday to Moscow authorities and the community to do more to lower that number.

"These losses are equal to a military campaign," Alexei Nikiforov, coordinator of the homeless assistance program run by the aid group, known in English as Doctors Without Borders, said Friday. "There is no war, but people are still dying."

Since September, the freezing temperatures have killed more than 270 people in the capital, according to data from city emergency medical workers. Some 2,200 people have been treated for frostbite, hypothermia or other cold-related illnesses.

Temperatures have warmed slightly in recent days but are expected to dip as low as -25 Celsius (-13 Fahrenheit) in the capital over the weekend.

Most cold victims in Moscow are homeless or drunk people who cannot find proper shelter and doze off in the open, medical officials say. Many are often forced out of warm public places such as subway and train stations by police.

Eight government-run homeless shelters serve this city of 10 million, with an estimated 100,000 homeless. But on any given night, even when temperatures drop as low as -31 Celsius (-24 Fahrenheit), the shelters often are not full.

A rule under which the shelters only accepted people with proof of past Moscow residency was waived in the middle of November. But homeless men gathered Friday outside a Doctors Without Borders medical center complained that they are often still referred to police when they show up at the hostels without proper documents.

An estimated 60 percent of Moscow's homeless have no identification documents.

Andrei Shchurok, leaning on a cane and looking decades older than his 27 years, said that because he has no documents, he spends most nights huddled in building entrances or underground passages. He is afraid to fully fall asleep and be woken by angry police.

"They are always taking from me and harassing me," said Shchurok.

In an open letter to Moscow authorities, Doctors Without Borders urged the government to open more temporary shelters on freezing days, and to ensure that anyone - with or without documents - is admitted.

Nikiforov suggested that Moscow's metro stations, which close shortly after 1 a.m., could be used.

He also urged the government to pursue more preventive measures toward homelessness, saying that many homeless people develop serious illnesses requiring expensive treatments, while routine medical consultations cost about 100 rubles (US$3).

But Nikiforov said the biggest hurdle is the attitude of most Russians, challenging citizens to shed what he said was their indifference.

"We are no longer a merciful people," he said. "We can walk over a person lying in the street, freezing in the cold."

An elderly woman interrupted the news conference outside the Doctors Without Borders medical center, yelling at Nikiforov for operating it in the central Moscow building whose residents she said she represented.

The woman, who would not give her name, complained that homeless and drunks loiter around the courtyard and streets. "We are suffering because of the people who hang around here," she said.

St. Petersburg, Russia's second-largest city, has also been especially hard-hit by cold this winter. The deep freeze has slowed traffic at the city's port as scores of ships wait for icebreakers to slam through ice up to a meter (3.5 feet) thick.

At the city's botanical garden, workers built large fires inside the main greenhouse to try to keep the tropical plants alive, but the banana tree, a favorite among visitors, has died.