NOVIYE ATAGI, Russia (AP) _ The Red Cross suspended all relief efforts and evacuated most of its staff from Chechnya today, a day after masked killers shot and killed four nurses and two other aid workers as they slept.

The attack, in which a seventh worker was wounded, was the bloodiest against the Red Cross in its 133-year history.

All sides in the breakaway Russian republic condemned the slaying, which cast a shadow over prospects for stability in the separatist region, where a truce has been in place since August.

The international Red Cross suspended all operations in Chechnya and evacuated about 35 workers. Only five staff members remained today to help with the investigation.

``Respect for the Red Cross and for humanitarian organizations in general has not prevailed in Chechnya,'' said Victoria Catliff, a Red Cross spokeswoman in Moscow.

Red Cross workers in Chechnya already had endured six kidnappings this year, and the agency reduced its staff earlier this month because of security concerns.

No one has claimed responsibility for the attack, but Russian and Chechen leaders speculate that the assailants were trying to wreck the republic's fragile peace, disrupt upcoming elections or discredit separatists who are now in charge.

The survivors and bodies of the slain workers were to be flown to Geneva later today, Catliff said.

As many as 15 attackers participated in the raid early Tuesday on the Red Cross' 3-month-old hospital in Noviye Atagi. Those killed were five women and one man from Canada, the Netherlands, Spain, New Zealand and Norway.

The killers arrived at 4 a.m. at the small cluster of buildings on a dirt road in the village 15 miles south of Grozny, the Chechen capital. They left without entering the main hospital building, which had 40 patients.

Jean de Courten, operations director for the international Red Cross, called the attack a cowardly ``deliberate assassination.''

``In the past years we have known tragic events at the Red Cross, but this one hits at the heart of the Red Cross and it hits at the motivation of every one of us who is working for the humanitarian good,'' he said, his voice trembling during an emotional briefing at the group's Geneva headquarters.

The Red Cross called it the single deadliest attack against its delegates _ the agency's highest field rank _ although 15 Red Cross people were killed in separate attacks in Somalia in 1992. It was the worst attack on foreigners since the war in Chechnya began two years ago.

Killed were Johan Elkerbout, 47, a Dutch construction technician; medical administrator Nancy Malloy, 51, of Vancouver, British Columbia; and four nurses _ Ingebjorg Foss, 42, and Gunnhild Myklebust, 50, of Norway; Sheryl Thayer, 40, of New Zealand; and Fernanda Calado, 49, of Spain.

Christophe Hensche, a Swiss national in charge of the hospital, was shot in the shoulder and survived by feigning death.

Few outside groups are left in Chechnya other than the Organization for Security and Cooperation in Europe, which said it was staying.

In Moscow, the lower house of parliament opened its session today with a minute of silence for the slain aid workers.

Yeltsin sent thousands of Russian troops into Chechnya in December 1994 to smash the republic's independence movement, but the troops became mired in a bloody, unpopular war. The last Russian combat troops are pulling out in advance of the elections set for Jan. 27.

Still, the pullout and the peace deal have enemies on both sides and tensions have been rising. Sporadic violence continues.

Chechen leaders today announced steps to improve security for foreign election observers, some of whom already have arrived.

The shaky peace made it possible for the Red Cross to open the hospital, its only one in Chechnya, in September with assurances of support from both sides.

Anxious relatives of 35 patients being treated at the hospital gathered at the compound today, afraid that the facility would be closed.

``This hospital was the only place that offered free and reliable medical help,'' said Khava Muradova, whose wounded son had gangrene and was supposed to have surgery today.