OKA, Quebec (AP) _ A shot was fired this morning as soldiers moved closer to the last area under control of armed Mohawk warriors.

There was no immediate indication which side fired the shot, but it did not appear anyone was hit. Both Mohawk and army spokesmen denied firing.

The incident took place as a 2-month-old standoff wore on today, with troops surrounding about 30 Mohawk Indian militants who refused to surrender and retreated to a drug and alcohol detoxification center on Indian land.

On Sunday, about 350 soliders demolished the last barricades blocking access to the Kanesatake Indian reservation, and seized control of most of it. Mohawks were confined to a small wooded area around the center.

Late Sunday, the militants issued a statement saying the army had given them an ultimatum to surrender by 8 a.m. EDT today or face attack. But an army spokesman, Maj. Jean-Paul Macdonald, said that was ''absolutely wrong.''

''The Canadian Forces are not in the business of giving ultimatums in such sensitive situations,'' Macdonald said.

Native representatives, including three chiefs from the Six Nations Iroquois Confederacy, met late into the night at the center to discuss ways to end the standoff without violence.

The Indians had errected the barricades at Kanesatake and another Mohawk community, Kahnawake, in a dispute over plans by Oka town officials to expand a golf course onto what they claim is tribal land.

The barriers had blocked traffic on an Oka highway and, about 20 miles away, on a bridge connecting Montreal to southern suburbs.

On Sunday, the Warriors, a militant Mohawk organization, periodically came out from the trees and stood face-to-face with soldiers at Oka. On one occasion, a Warrior approached a soldier, stood chest-to-chest with him and stared into his eyes as a group of reporters watched.

Finally, he let out a war whoop, turned and walked away. ''I want to see their face before I kill them,'' the Warrior said.

The Mohawks fortified their positions by using a front-end loader to pile earth on a road near the two-story detoxification center in the woods. Some crouched behind trees in wait for the army.

When asked whether the Warriors were prepared to shoot it out with the army, one militant said ''definitely.''

''This is it. We can't be pushed any further,'' he said.

However, no fighting broke out between the soldiers and Indians Sunday. Military helicopters flew overhead and about 80 armored vehicles were in the area, the army said.

Mohawk spokesman Ellen Gabriel said the Indians are ''pretty squeezed in right now. There's no way out really.''

Last week, Quebec Premier Robert Bourassa ordered the army to dismantle the barricades.

The army moved into the Kanesatake Mohawk settlement in Oka, 18 miles west of Montreal, Saturday afternoon after factional fighting broke out between moderate and militant Mohawks. Two Indians were hurt before the army moved in.

When the soldiers pushed forward, only one shot was fired by a Mohawk on Saturday, said army commander Lt. Col. Pierre Daigle. There were no casualties.

The dispute over the golf course expansion was solved when the federal government purchased the land and said it would give it to the Indians.

But the Mohawks seized the situation to publicize a much wider range of grievances, including demands for sovereignty, and their campaign caused numerous brief sympathy blockades across Canada.

One week ago, provincial authorities gave the military the go-ahead to end the armed standoff that began July 11 when the Quebec provincial police attempted to storm the Mohawk barricade at Oka. One officer was killed in that assault, but it is still not clear by whose gunfire.