Taliban guerrillas attacked a convoy of provincial officials and police in the southern province of Helmand, killing three policemen and wounding six, government officials said on Tuesday.
In a separate incident, four Afghan aid workers were killed by a roadside blast west of Kabul, police said.
The attacks come after several days of some of the heaviest Taliban attacks since they were ousted in 2001 and just as NATO is bringing thousands of extra troops into the country.
On Monday, U.S. warplanes hunting Taliban fighters bombed a religious school and mud-brick homes in southern Afghanistan, killing dozens of suspected militants and 17 civilians. It was one of the deadliest strikes since the American-led invasion in 2001.
More than 250 people have been killed since last Wednesday -- more than the number reported killed in Iraq during the same period -- according to figures from the U.S. military and Afghan authorities.
Most of the dead were militants but included dozens of Afghan police and troops, four foreign soldiers and civilians.
The government convoy, that included the provincial police chief, was travelling in the north of Helmand when it came under attack late on Monday, a provincial official said.
“Three policemen were martyred and six were wounded,” said Interior Ministry spokesman Yousuf Stanizai. He said there were also Taliban casualties but he had no details.
A Taliban spokesman, Qari Mohammad Yousuf, claimed responsibility for the attack and said there were no Taliban casualties.
The chief of police in Maidan-Wardak province, Subhan Qul, said four aid workers, one of them a woman, were killed when their vehicle was hit by a roadside bomb on Monday.
He said they worked for the Afghan aid group AHDA but he did not know what that stood for.
An official at an agency overseeing security for aid workers in Afghanistan said he had heard that a civilian car had been hit by a bomb or mine in the province just west of Kabul, but he had yet to confirm details of the attack.
Taliban organized and aggressive
The Taliban, fighting to expel foreign forces and defeat the Western-backed government, have attacked and killed aid workers in the past, accusing them of supporting the government.
Nearly five years after they were forced from power by U.S. and Afghan forces, the Taliban appear better organized and more aggressive than at any time since their ouster.
The militants have not managed to capture and hold territory but ever larger swathes of the countryside are off limits to government and aid workers at a time the government should be pushing its authority and development work into rural areas.
The violence is also disastrous for Afghan efforts to attract investment, economists say.
President Hamid Karzai invited investors from the United Arab Emirates to come to his country, in a speech there on Monday, as news was emerging from southern Afghanistan of scores killed in fighting.