Two U.S. warplanes accidentally strafed their own NATO forces in southern Afghanistan on Monday, killing one Canadian soldier and wounding more than 30 others.

The soldier has been identified as Pte. Mark Anthony Graham, a member of 1st Battalion, The Royal Canadian Regiment, based in eastern Ontario's CFB Petawawa.

The friendly fire incident occurred around 5:30 a.m. when soldiers trying to seize a Taliban stronghold along the Arghandab River requested air support.

NATO said in a statement that the International Security Assistance Force provided the support but "regrettably engaged friendly forces during a strafing run, using cannons." It later identified the planes as U.S. A-10 Thunderbolts.

NATO spokesman Maj. Scott Lundy said five of the more than 30 wounded soldiers were seriously injured and evacuated out of Afghanistan for medical treatment.

"It was a scene of absolute chaos this morning at the airport near the hospital. We were there as helicopter after helicopter ferried in the wounded," CTV's Matt McClure reported from Kandahar.

Brig.-Gen. David Fraser, the Canadian in charge of NATO forces in southern Afghanistan, said Operation Medusa will continue despite the casualties.

"This has been a tough hit, but Canadians are continuing the fight," he said in a statement released Monday.

CTV News has learned that the United States will launch its own probe into the incident, in addition to a NATO investigation currently underway.

"There has not been any official reaction from the United States government, but CTV News has learned Ambassador David Wilkins -- the U.S. ambassador in Canada -- phoned Prime Minister Stephen Harper first thing this morning," CTV's David Akin told Newsnet.

Wilkins expressed the regret of the U.S. government over the tragedy, and also indicated the government would launch its own investigation.

In Afghanistan, Fraser told reporters that friendly fire incidents are always a risk that soldiers must face.

"We do have procedures, we do have communications, we do have training and tactics and techniques and procedures to mitigate the risk but we can't reduce those risks to zero,'' he said in a news conference at Kandahar Airfield.

"The Canadian forces and the rest of armed forces of the world and the international community wouldn't be here if it wasn't dangerous.''

Monday's friendly fire incident was the second such incident since Canadians began operations in Afghanistan more than four years ago.

Four soldiers were killed and eight others wounded in April 2002 when an American F-16 fighter mistakenly bombed Canadians on pre-dawn training exercise.

The friendly fire death comes just one day after another four Canadian soldiers were killed and six wounded during Operation Medusa, a mission aimed at purging militants from the Taliban stronghold of the Panjwaii district west of Kandahar.

Two of the dead were identified Sunday as Warrant Officer Frank Mellish and Warrant Officer Richard Nolan, both of 1st Battalion, Royal Canadian Regiment, based at CFB Petawawa, Ont.

The third was identified Monday as Sgt. Shane Stachnik of 2 Combat Engineer Regiment based in Petawawa.

The name of the fourth was still being withheld at the request of the family.

Mellish was born in the small Nova Scotia town of Truro. The town lost another soldier just last month -- Cpl. Christopher Reid, killed during a battle with insurgents on Aug. 3.

"It's quite a shock," said Truro Mayor Bill Mills. "When I first heard the story this morning ... I had no idea that one of those gentlemen was from our area."

The battle continues

The past two days' deaths occurred as part of Operation Medusa, aimed at purging Taliban insurgents from the dangerous Panjwaii area, the site of intense fighting in recent weeks.

Taliban insurgents put up a stiff fight, using small arms and rocket propelled grenades to defend their positions.

Despite the casualties, NATO officials are maintaining that the offensive has been a success, estimating that 200 Taliban militants had been killed and 80 seized.

But a Taliban leader in south and southeastern Afghanistan rejected those claims as propaganda.

"They are saying that they have killed 200 Taliban but they did not kill even 10," Mullah Dadullah told the Associated Press in a satellite phone call from an undisclosed location.

Dadullah also warned that his fighters would "target" journalists who reported "wrong information."

The latest fatalities came as NDP Leader Jack Layton repeated his call for ending the Afghanistan mission in February 2007.

"Young people have stepped forward to put their lives on the line, fulfilling a mission that they were asked to fulfill," Layton told reporters in Toronto.

"What we as Canadians need to do is consider whether this is indeed the right mission for Canada going forward. Our view is that it is the wrong mission."

Prime Minister Stephen Harper did not address the possibility of a troop withdrawal in a statement on Sunday, in which he offered his condolences to the friends and families of those killed.

"We are proud of these soldiers' contribution to bring stability and hope to the people of Afghanistan," said Harper.

"These soldiers lost their lives in the service of their country. Canada is grateful for that service, and saddened by this loss."

In total, 32 Canadian soldiers and one diplomat have been killed in Afghanistan since 2002.

With files from The Canadian Press and The Associated Press