An explosion in eastern Afghanistan killed two NATO soldiers and one civilian, while attacks elsewhere in the country left seven policemen dead, officials said Wednesday.

Two other NATO soldiers were wounded when the blast hit troops on patrol in Sabari district of Khost province Wednesday, the alliance said in a statement.

The wounded soldiers were evacuated to a military hospital for treatment, the statement said.

NATO didn't release the soldiers' nationalities. However, most of the foreign troops in that area are American.

Militants trying to weaken the grip of U.S.-backed Afghan President Hamid Karzai have turned to roadside and homicide bomb attacks against heavily armed foreign troops.

They have also targeted Afghan police, whose lack of training and arms make them softer targets.

Over 1,200 people, mostly militants, have died so far this year in insurgency-related violence in Afghanistan, according to an Associated Press count.

Elsewhere, a roadside bomb destroyed a police vehicle near the provincial capital, killing two officers, said Wazir Pacha, a spokesman for the Khost police chief.

Also in Khost, police said a vehicle filled with explosives detonated near a police barracks, killing the driver and wounding a woman and a child who were outside. The blast appeared to be premature and the dead man was suspected of being a homicide bomber.

In central Ghazni province, militants attacked a police patrol in Muqur district, leaving four officers dead and two others wounded, said Maj. Martin O'Donnell, a NATO spokesman.

In Laghman province, also in the east, poppy farmers attacked a police force sent to eradicate their opium fields, killing an officer and wounding four others, provincial government spokesman Abdul Wakil Attak said.

Afghanistan produces over 93 percent of the world's opium. Some of the proceeds from the multibillion dollar illicit trade go to fund the insurgency.

The U.S.-led coalition said it detained 13 suspected militants during a raid with Afghan troops on Tuesday in Paktia province. Troops found weapons and ammunition in a search of the compounds, it said.