American and Afghan army forces killed at least 136 Taliban fighters over three days in western Afghanistan, the U.S. military said Monday.

The offensive took place in the western province of Herat, an area that lies near the Afghan border with Iran. The province, until recently, has seen much less violence than the southern province of Kandahar, where more than 2,000 Canadian troops are stationed.

The U.S. military said in a statement that U.S. troops, along with Afghan army troops and police, came across a Taliban position while on patrol in Herat province. They attacked using mortars, small arms fire and rocket-propelled grenades over three days.

On the last day of the offensive, NATO-led troops were called in to support the U.S.-led forces. NATO is leading the International Security Assistance Force, a coalition of 30,000 troops from 37 countries, now covering all of Afghanistan.

Major Chris Belcher, spokesperson for the U.S. army, said the so-called spring offensive by the Taliban has not materialized.

"We've been here for six years, and each year, they have promised a spring offensive. But we're still here," Belcher said.

According to the statement, the Taliban deaths occurred in two separate battles in Herat's Zerkoh Valley. In the first, 49 Taliban and one U.S. soldier were killed. In the second, 87 Taliban fighters were killed over 14 hours.

The number of dead could not be confirmed independently.

In other violence, near the Canadian base in Kandahar early Monday, a suicide bomber killed one person in an attack. Kandahar's police chief said the man killed was working for a private security company. No Canadian soldiers were involved in the incident.

Meanwhile, more than 2,000 NATO and Afghan troops have launched another military operation in the southwestern Afghan province of Helmand.

Led by the British, Operation Silicon is the latest effort to boost the authority of the Afghan government of President Hamid Karzai.

It involves about 1,100 British troops and 600 U.S. soldiers, with the remaining number from Canada, the Netherlands, Denmark and Estonia. The operation includes Afghan troops as well.

Lt.-Col. Stuart Carver, a British commander, said the operation is targeting Helmand's Sangin Valley, an area near a ring road in Afghanistan still under partial Taliban control.

"It is all part of a longer-term plan to restore the whole of Helmand to government control," Carver said.
  
"You have to do it a piece at a time."

With files from the Associated Press