An 18-year-old woman working on rural development for the Afghan government was shot dead in the country's biggest southern city Kandahar on Tuesday, a local official said.

Rabia Sadat was killed as she left home in central Kandahar to go to work at around 8:00 am (03:30 GMT), provincial spokesman Zalmai Ayoubi said.

A policeman and four Taliban insurgents were killed overnight when militants attacked government offices in central Afghanistan, the local police chief said Monday.

The attack in the Qarabagh district of Ghazni province lasted about an hour and started when the Taliban launched two rockets at the district's administrative headquarters before opening fire on a police checkpoint nearby.

Five members of the same family were killed Saturday when a roadside bomb ripped through their minivan in insurgency-hit southern Afghanistan, an official said.

The incident happened in Gereshk, a volatile district of Helmand province, as the family traveled to Helmand's main town Lashkar Gah, provincial spokesman Daud Ahmadi said.

An Afghan police commander on Wednesday accused international troops of killing two policemen by accident in one of the most potent Taliban strongholds in the south.

Kandahar provincial police chief Abdul Raziq said the victims were members of the Afghan Local Police (ALP), an anti-Taliban initiative in which local people are recruited to protect their own villages.

Around 200 Afghans burned tyres and blocked key roads near the presidential palace Tuesday in angry protest after bodyguards of a lawmaker allegedly killed at least one person over a land dispute.

The unrest flared just southeast of the Afghan capital Kabul when members of the Kuchi nomadic tribe clashed with guards working for the lawmaker.

U.S. President Barack Obama on Saturday hailed the "extraordinary sacrifices" made by the 31 U.S. soldiers killed in Afghanistan when, according to local officials, the Taliban shot down their helicopter.

Obama also paid tribute to the seven Afghan soldiers killed during an anti-Taliban operation late Friday when a rocket fired by the insurgents struck their Chinook helicopter in Wardak province, southwest of the capital Kabul.

A total of 31 members of the U.S. special forces have died in a helicopter crash in eastern Afghanistan along with seven Afghans, a statement from Afghan President Hamid Karzai's office said Saturday.

"The president of the Islamic Republic of Afghanistan Hamid Karzai expressed condolences over a NATO helicopter crash and the deaths of 31 members of U.S. special forces," the statement said.

A bomb attack killed an Afghan intelligence agent and wounded three girls in the country's north on Thursday, a provincial spokesman said, with the Taliban claiming responsibility.

Payenda Mohammad, a junior official in the Kunduz branch of Afghanistan's National Directorate of Security (NDS), died when the blast destroyed his car near his home, provincial spokesman Mahboobullah Sayedi told Agence France Presse.

United States ambassador to Afghanistan Ryan Crocker took office on Monday, joining a new general at the helm as the U.S.-led mission looks to transfer responsibility to Afghans and exit the country.

Veteran diplomat Crocker took over from outgoing Ambassador Karl Eikenberry, whose fraught relations with Afghan President Hamid Karzai were documented extensively in leaked cables revealed in December.

Pakistani officials on Tuesday accused the Afghan army of firing mortar bombs across the border, killing four Pakistani soldiers and stepping up a recent surge of cross-border violence.

The officials said two other soldiers were wounded in the attack in South Waziristan, part of the lawless tribal district on Pakistan's border with Afghanistan that Washington has called the global headquarters of al-Qaida.