Updated

Militants attacked a coalition forces base in southern Afghanistan on Wednesday, sparking a fierce battle that killed 32 suspected Taliban militants and two troops — one American and one Canadian, officials said.

The battle in Helmand province's Sangin district also wounded three Canadian soldiers, Canadian Brig. Gen. David Fraser told reporters at a base in southern Kandahar city. In addition, a U.S. military statement said an American soldier was hurt.

The fighting was the deadliest in months and highlights the threat rebels still pose four years after the Taliban was ousted by U.S.-led coalition forces. Direct attacks on foreign bases are unusual, and Wednesday's assault comes after the Taliban warned of a renewed offensive this year.

The attack followed separate roadside bombings in the region Tuesday that killed six Afghan soldiers and four private security workers, respectively. Officials blamed both bombings on Taliban rebels. Suspected Taliban rebels also attacked a police checkpoint in Kandahar city late Tuesday, killing two officers and wounding four, police said.

Coalition forces killed 12 militants in the initial attack on the base in Sangin, while another 20 insurgents were killed as they fled, a U.S. military statement said.

Large caches of weapons, bombs and ammunition were discovered at the Taliban compound after the battle. All were blown up and the compound was destroyed, the military said.

The U.S. military said one of the slain coalition soldiers was American, but did not identify him, pending notification of next of kin. Fraser said the slain Canadian was Pvt. Robert Costall of the 1st Battalion of the Princess Patricia's Canadian Light Infantry, based in Edmonton, Alberta.

The wounded soldiers were rushed for treatment to a base in Kandahar.

It was not immediately clear if the violence was linked to Afghanistan's drug trade. Helmand is Afghanistan's main opium poppy-growing region and there have been fears of widespread violence since an aggressive poppy eradication campaign started in recent weeks.

Helmand's rugged mountains are also popular hiding places for Taliban rebels, many of whom are believed to slip back and forth across the province's largely unguarded border with Pakistan.

One of Tuesday's roadside bombings struck an army vehicle on a road in Helmand province northwest of Kandahar, killing six Afghan soldiers, said Gen. Rehmatullah Raufi, a top Afghan army official in the province. He blamed the Taliban for the attack, but offered no evidence.

"We know that it is the work of Taliban terrorists, and our forces are trying to trace and capture them," he told The Associated Press.

Hours earlier, a roadside bomb exploded as a Namibian and three Afghans working for Houston-based U.S. Protection and Investigations were driving in a convoy on the main road linking Kandahar city with Herat, the main city in western Afghanistan. The company provides security for a construction company in the area.

Bill Dupre, the firm's deputy managing director in Kabul, said the victims' vehicle caught the "full brunt" of the remote-controlled bomb blast, killing the four instantly. Several other vehicles in the convoy returned to their camp safely, he said.

Nimroz Gov. Ghulam Dusthaqir Azad blamed the Taliban for that assault, as well.