KABUL (AP) -- Bomb blasts killed four U.S. Marines in southern Afghanistan, where thousands of American troops have deployed in recent weeks as part of an offensive in the country's dangerous drug-producing region, an official said Sunday.
The four Marines died Saturday in Helmand province, where about 4,000 troops this month launched the largest Marine operation in Afghanistan since 2001. U.S. forces have met little resistance but face the danger of roadside bombs everywhere they travel.
A fifth U.S. service member wounded in June died of wounds in the U.S. on Friday, said Lt. Cmdr. Christine Sidenstricker, who confirmed the deaths of the four Marines. The four killed Saturday were initially identified as Army soldiers.
The five deaths bring to 106 the number of U.S. troops killed in Afghanistan this year - a record pace. Last year 151 U.S. troops died in the country.
The U.S. casualties come on the heels of eight British deaths in Helmand during a 24-hour period that ended Friday, deaths that have triggered a debate in Britain about its role in Afghanistan. Britain has now lost more troops in Afghanistan than it did in Iraq.
President Barack Obama called Britain's contribution critically important in an interview with Sky News broadcast Sunday .
"My heart goes out to the families of those British soldiers," he said. "Great Britain has played an extraordinary role in this coalition, understanding that we cannot allow either Afghanistan or Pakistan to be a safe haven for al-Qaida, those who with impunity blow up train stations in London or buildings in New York."
Obama ordered 21,000 additional U.S. troops to Afghanistan earlier this year to help quell an increasingly violent Taliban insurgency. Some 10,000 Marines and 4,000 soldiers from the Stryker Brigade - the 5th Brigade, 2nd Infantry Division based in Fort Lewis, Washington - are deploying in the south, the Taliban's spiritual birthplace and stronghold.
The troops are expected to help provide security for the country's August presidential election and help train army and police units who U.S. officials hope can one day provide security for the country.
In other violence around the country, international troops and Afghan police killed 12 Taliban insurgents in a gunbattle in southern Afghanistan, police said Sunday.
The joint force attacked a compound north of the capital of Uruzgan province where the militants were hiding Saturday evening, sparking the fighting, police spokesman Mohammad Musa said. He said no Afghan police or international troops were killed.
In eastern Kunar province, meanwhile, one civilian was killed and five wounded when shelling from a gunbattle between insurgents and Afghan and international forces hit a house.
Provincial Police Chief Gen. Abdul Jalal Jalal said everyone in the house initially survived Saturday's blast, but one man died from his injuries after being rushed to a hospital. Jalal said it was unclear which side fired the shots that hit the house.
Also Saturday, at least six police officers were killed by roadside bombs - two in southern Helmand province and at least four south of Kabul in Logar province, officials said.
In Logar, the officers were driving in a private car in Charkh district when the explosion hit, said provincial police chief Gen. Mustafa Mosseini.
NATO forces, who secured the site and treated one wounded officer, said in a statement that four police were killed. Mosseini said five officers died.
The bombing in Helmand took place Saturday night in Lashkar Gah, the provincial capital, killing two police and wounding three, said Dawood Ahmadi, the governor's spokesman.
Police officers are regular targets of Taliban and other insurgents in Afghanistan. Mosseini said the officers had been traveling in a civilian car in order to avoid drawing the attention of potential attackers.
In another gunbattle in eastern Paktia province between insurgents and Afghan police, two militants and one police officer were killed, said Rahullah Samon, a spokesman for the governor.