KABUL, Afghanistan --A female British aid worker kidnaped during an ambush last month was killed during a rescue attempt by NATO forces in northeastern Afghanistan, Britain's foreign secretary said Saturday. The announcement came as four Italian troops were killed and one seriously wounded in an insurgent ambush Saturday in the country's west. Violence continues unabated throughout much of Afghanistan. The focus of the U.S.-led war, which entered its 10th year last week, has been on the south, but coalition troops are fighting resilient militants in both the east and north. The aid worker, identified as Linda Norgrove, was killed Friday night by her captors during the operation to free her, Foreign Secretary William Hague said in a statement from London. Norgrove and three Afghan colleagues were kidnapped in eastern Kunar province on Sept. 26 after being ambushed. Police fought a gunbattle with the kidnappers near the attack site before the assailants fled. "It is with deep sadness that I must confirm that Linda Norgrove ... was killed at the hands of her captors in the course of a rescue attempt last night," said Hague. "Working with our allies we received information about where Linda was being held and we decided that, given the danger she was facing, her best chance of safe release was to act on that information," Hague said. Norgrove's three colleagues were released shortly after being abducted. Details about the failed raid were sketchy. It was unclear if any other deaths occurred during the assault. Meanwhile, the four Italian soldiers were killed in a roadside bomb blast Saturday in western Farah province and another was wounded seriously, said Gen. Massimo Fogari, a spokesman for Italy's Defense Ministry. The bomb exploded as a 70-vehicle convoy passed by insurgents, and then the soldiers came under small-arms fire. "Four soldiers were killed in the explosion and one was injured," Fogari told Sky Italia. "It's an ambush typical of the asymmetrical war that is being fought in Afghanistan." Prime Minister Silvio Berlusconi said he was saddened "by the tragic ambush." "We are grateful to all Italian soldiers who, in various missions around the world, allow our country to keep its international commitments in support of peace and against any form of terrorism," Berlusconi said in a statement. The deaths brought to 24 the number of NATO forces killed this month. At least 2,012 NATO service members have died since the U.S.-led invasion of Afghanistan on Oct. 7, 2001, according to an Associated Press count. Friday's attempted rescue operation wasn't the first of an abducted Briton in Afghanistan to end in bloodshed. New York Times reporter Stephen Farrell and translator and reporter Sultan Munadi were taken hostage in September 2009 when they went to cover a NATO airstrike that killed scores of civilians in northern Afghanistan. Munadi and a British commando died in the raid that rescued Farrell. In August, unidentified gunmen killed 10 members of a charity medical team, including Briton Dr. Karen Woo, six Americans, a German and two Afghans. The aid workers for the International Assistance Mission were shot and killed by militants in Badakhshan province, which neighbors Kunar to the north, as they returned from providing health care in remote villages. Northern Afghanistan has been the scene of escalating violence amid intensified military operations by NATO and Afghan forces. Saturday's events came a day after a powerful blast at a mosque packed with worshippers killed at least 20 people -- including a provincial governor -- in Taluqan, capital of northern Takhar province. Thirty-five others were wounded in the brazen attack. The bomb targeted and killed Mohammad Omar, governor of neighboring Kunduz province, and came just days after he publicly warned of escalating threats from Taliban and foreign fighters across the north. No group claimed responsibility, but the Taliban have targeted Omar previously. Meanwhile, President Hamid Karzai flew to volatile southern Afghanistan to meet with more than 200 tribal elders and seek their support for his government's effort to extend its influence beyond Kabul. Karzai was accompanied by Gen. David Petraeus, the top commander of U.S. and NATO forces in Afghanistan, U.S. Ambassador Karl Eikenberry and top Afghan security force officials on the trip to troubled Kanadhar province. Kandahar is the scene of NATO's Operation Dragon Strike, targeting the Taliban in their southern strongholds. The operation aims to rout insurgents from areas they have long controlled. In other violence, NATO and Afghan forces killed two senior Taliban leaders and two other fighters after raiding a compound in eastern Afghanistan, the military alliance said Saturday. Mullah Hezbollah, who operated in Wardak province, died in a gunbattle during an operation Thursday night, NATO said. Another Taliban leader, Qari Sulayman, was also killed along with the two other insurgents in the raid. NATO also announced Saturday joint forces seized more than 6,600 pounds (3,000 kilograms) of drugs -- including heroin and opium -- a day earlier from vehicles searched in southern Afghanistan.