KANDAHAR, Afghanistan - Taliban militants ambushed a group of police while they were eating lunch in remote southern Afghanistan, killing 20 and fatally shooting the mother of one as she pleaded unsuccessfully for her son's life, an official said Thursday.

A Taliban spokesman, Qari Yousef Ahmadi, said two militants were killed and four wounded in the ambush Wednesday in Helmand province. Ahmadi claimed 32 police were killed, but Afghan officials put the toll at 20, plus the mother.

Afghan police have less training and weapons than Afghan soldiers, and they often bear the brunt of Taliban attacks. At least 870 police were killed in attacks in 2008, including the 20 in Helmand. Some 925 died in 2007.

Violence in Afghanistan has spiked in the last two years, and Taliban militants now control wide swaths of countryside. In what amounts to an Afghan version of the surge in Iraq, the U.S. is preparing to pour at least 20,000 extra troops into the south, including Helmand. President-elect Barack Obama wants to increase the U.S. military presence in Afghanistan as the U.S. pulls back in Iraq.

Wednesday's attack targeted a police post in the small village of Shaghzay in the district of Kajaki in Helmand province, said Daud Ahmadi, spokesman for Helmand's governor. He said the attack happened while the police were eating lunch and the mother of one of the police, who pleaded with the militants to spare her son's life, was also killed.

The 20 policemen killed were bodyguards for the district chief of the nearby town of Musa Qala, Ahmadi said. Musa Qala for many months in 2007 had been held by Taliban fighters.

The region between Musa Qala and Kajaki is filled with Taliban militants, and the Afghan government has little control outside of main district centers. Taliban fighters operate their own parallel government in the region, sometimes called a shadow government.

The Taliban's shadow police chief for Helmand province, Mullah Mohammad Qassim, claimed in a call to The Associated Press that one of the policemen in the group of bodyguards was a Taliban sympathizer and had helped set up the ambush. There was no way to confirm the claim.

In other developments, NATO said two of its soldiers were killed in southern Afghanistan on Wednesday. One was identified as British. The second soldier's nationality was not immediately released.

NATO has about 12,500 forces in Afghanistan and the U.S. has some 32,000.

A record 151 U.S. forces died in Afghanistan in 2008, the deadliest year yet in a seven-year war that military officials say is likely to get even bloodier in 2009, as thousands more American troops pour into the country.

The number of roadside bombs doubled from the year before to roughly 2,000, with many of the devices more powerful than in previous years.