KABUL, Afghanistan – Five NATO troops died in roadside bomb attacks in Afghanistan, the alliance said Saturday, as international forces announced that they had foiled a terrorist attack on an upcoming conference in Kabul to be attended by leaders from more than 60 nations.

Security is being tightened across the capital for Tuesday’s conference, which is attracting the heads of NATO, the United Nations and top diplomats, including Secretary of State Hillary Rodham Clinton.

In May, Taliban fighters had a gunbattle with security forces and militants launched a rocket that landed about 100 yards from the site of a national peace conference in the capital. Three civilians, but no conference delegates, were wounded.

Acting on intelligence, a combined international and Afghan commando force captured a Taliban bomb-making expert Friday night in Kabul, NATO said.

Neither Afghan nor NATO officials would identify the suspect, give details of the plot or say how advanced the planning was. But the Afghan Defense Ministry said several “enemies of the people” were killed in the raid and 26 suspected insurgents were arrested.

The ministry said a special Afghan army commando unit based with U.S. special forces outside Kabul carried out the raid in the southwestern district of Wasel Abad in the capital city.

Elsewhere, three international service members were killed by homemade bombs Saturday, including an American in eastern Afghanistan and a British soldier in the south, NATO and Britain’s Defense Ministry said. A third service member died Saturday in the south, but NATO did not disclose the nationality or any details of the attacks.

Two others — a British marine and an American service member — died in an explosion Friday in the south, the alliance and the U.K. government said. Britain also said one of its airmen died in a traffic accident Friday.

In Kandahar, an Afghan police officer was shot and killed Saturday evening, said Mohammad Shah Farooqi, head of the crime and investigation department of the province’s police.

The deaths added to a summer of escalating violence as Afghan and coalition forces step up patrols in the Taliban-dominated south in a push to wrest control of the traditional insurgent stronghold. Last month was the deadliest of the nearly nine-year-old war for international troops, with 103 killed, including 60 Americans. So far in July, 54 international troops have died, 39 of them American.

Homemade bombs are the leading cause of death to both troops and civilians. The United States is sending $3 billion worth of detection equipment and bomb-resistant vehicles to Afghanistan, the Defense Department said this month.