PORT-AU-PRINCE, Haiti — UN peacekeepers kept watch in a volatile slum Monday as calm returned to Haiti's capital a day after peacekeepers and police took over the stronghold of militants loyal to ousted President Jean-Bertrand Aristide.

Markets and stores opened as usual in Port-au-Prince, while police patrolled the streets in large numbers and a United Nations helicopter circled overhead. One police officer was shot and killed in Sunday's operation in the Bel Air slum as scores of troops and about 100 police officers from Canada, France, Spain and Benin moved in. They were led by 10 Brazilian armoured cars with mounted submachine-guns.

"The joint operation was a great success," UN mission spokesman Damien Onses-Cardona said Monday.

A police officer at the scene on Sunday said at least two "bandits" were killed and several civilians wounded in the operation.

Brazilian Defence Minister Jose Viegas said Brazilian troops who are leading the UN force should stay in Haiti "at least one year more."

In an interview published Monday in the Folha de Sao Paulo newspaper, Viegas was quoted as saying "it is evident, and the whole world expects it, that there should be an extension" of the UN mission.

UN peacekeepers, who took over from a U.S.-led force in June, were initially given a six-month mandate to help stabilize Haiti.

Interim Prime Minister Gerard Latortue on Saturday castigated the United Nations, saying it had not sent enough troops to prevent recent violence. There are 3,200 peacekeepers in the Caribbean country, instead of the promised 8,700.

Sunday's Operation Clean Sweep Bel Air came after the interim government said it would root out gangs that it blamed for violence that had killed at least 56 people in the previous three weeks.

Aristide supporters say police started the violence by shooting and killing two protesters at a Sept. 30 march held to demand the return of Aristide, who left amid a rebellion on Feb. 29.

Aristide was accused of corruption, profiting from cocaine smuggling and using police to suppress his opponents. He left Haiti on a U.S.-chartered plane as ex-soldiers leading a bloody rebellion neared Port-au-Prince.

Now in South Africa, Aristide has accused the United States of orchestrating his ouster and insists he remains Haiti's democratically elected leader.

UN peacekeepers remained in parts of Bel Air on Monday, keeping watch 24 hours a day, after police and peacekeepers had cleared some 130 carcasses of vehicles from the streets, Onses-Cardona said.

Troops also were ensuring security at the capital's port, allowing the transport of aid shipments bound for flood-stricken northern Haiti, Onses-Cardona said. Last month tropical storm Jeanne killed 1,900 people and left 900 others missing and presumed dead, many in the northwestern city of Gonaives.

Amid the violence in the capital, gunmen highjacked an ambulance of the Haitian Red Cross during the night, the International Committee of the Red Cross said Monday.

The gunmen stopped the ambulance and ordered the driver out near the midtown Nazon district, where unidentified arsonists also set two vehicles afire before dawn, the ICRC said.