Kabul, Afghanistan ? Roadside bombs in southern Afghanistan on Sunday left seven NATO soldiers dead, the alliance said, as its forces continued an anti-Taliban offensive in the world’s most fertile opium-producing region.

Separately, a purported spokesman for the Taliban said the kidnapped translator for an Italian journalist was beheaded Sunday. The Afghan government confirmed the death.

Six troops died and one was injured when one of the roadside bombs struck their vehicle, the alliance said in a statement. Canadian Prime Minister Stephen Harper confirmed they were Canadian troops, Canadian Press reported.

A separate roadside bomb Sunday killed one NATO soldier and wounded two, NATO said.

Officials did not release the nationality of those soldiers and did not give details or say where exactly in the south the attacks took place.

The Canadians’ deaths appeared to be the biggest single combat loss for foreign troops in Afghanistan since June 2005, when a U.S. helicopter crashed. Sixteen American troops died after the aircraft was apparently hit by a rocket-propelled grenade.

The fatalities underline how virulent Afghanistan’s Taliban-led resistance remains, more than five years after a U.S.-led invasion drove the hardline militia from power for harboring al-Qaida.

Elsewhere in southern Afghanistan, freelance journalist and translator Ajmal Naqshbandi was beheaded after more than a month in captivity. He had been kidnapped along with Italian journalist Daniele Mastrogiacomo and a driver, who had been beheaded earlier.

Mastrogiacomo, who worked for the daily La Repubblica, was released March 19 in a much criticized swap for five Taliban militants.

The Taliban made a similar demand in return for Naqshbandi’s release.

“We asked for two Taliban commanders to be released in exchange for Ajmal Naqshbandi, but the government did not care for our demands, and today, at 3:05 p.m., we beheaded Ajmal in Garmsir district of Helmand province,” said Shahabuddin Atal, who claimed to be a spokesman for regional Taliban commander Mullah Dadullah.

“When we demanded the exchange for the Italian journalist, the government released the prisoners, but for the Afghan journalist, the government did not care,” Atal said.