U.S.-led coalition troops foiled an insurgent ambush in southern Afghanistan, killing 18 suspected militants, a military statement said Tuesday.

Some 60 insurgents attacked the troops Monday with heavy machine-guns and rocket-propelled grenades in the Cahar Cineh district of the southern Uruzgan province, the statement said. There were no coalition casualties.

Three insurgents also were captured for questioning, the statement said.

Earlier Tuesday, a suicide car bomber struck a NATO-Afghan military convoy, killing two civilians and wounding one, officials said.

A remote-controlled bomb in Helmand province also killed two police on patrol Tuesday, an official said.

The suicide bomber in a white Toyota car hit the military convoy on a road linking Kandahar with the city's airport, said Maj. Scott Lundy, a NATO spokesman. No NATO soldiers were wounded. One NATO vehicle was damaged, he said.

A NATO statement said two Afghan civilians were killed and one wounded.

The Taliban have increased suicide attacks this year, borrowing tactics from militants in Iraq. The escalation in the Taliban insurgency has stoked bitter fighting. More than 1,600 people, mostly militants, have died across Afghanistan in the past four months, according to an Associated Press tally of reports by U.S., NATO and Afghan officials.

A remote-controlled bomb hit a police vehicle on patrol in Grieshk district of Helmand province, killing two officers, said Ghulam Muhiddin, the Helmand governor's spokesman. He blamed the Taliban.

CountryWatch: Afghanistan

Another remote-controlled bomb went off in east Kabul shortly after a NATO vehicle patrol drove past, but there were no casualties, said Interior Ministry spokesman Yousef Stanezai.

Meanwhile, two New Zealand soldiers serving in Afghanistan's Bamiyan province were airlifted to a military hospital after being injured in a road accident, a New Zealand defense spokesman said Tuesday. The soldiers were injured when the part of the road they were on gave way, causing their vehicle to roll down a 65-foot slope.