Daughters and relatives of Ms Zaki weep by her coffin

Zakia Zaki was shot seven times, including in the chest and head, as she slept with her 20-month-old son at her home north of Kabul, officials say.

The governor of Parvan province, where the attack took place, told the BBC he did not know who killed her. No one has admitted carrying out the attack.

Her murder came just days after a woman newsreader was killed for reasons which were described as "family-related".

'Act of terror'

The Parvan governor, Abdul Jabbar Taqwa, visited the scene of the killing in the town of Jabal as Siraj, about 70km (40 miles) north of the capital.

Ms Zaki (centre) was a rare female voice in Afghanistan

He said the attackers were three men armed with pistols and rifles, who broke into Ms Zaki's house and got into the bedroom.

An older son, aged three, was with her at the time of the attack, but none of her six children was injured.

The Interior Ministry condemned what it called "this act of terror" and said it was trying to track down the perpetrators.

Zakia Zaki, was 35 years old and worked as a reporter and a schoolteacher.

She was one of the few female journalists in the country to speak out during the Taleban's rule.

She had also headed the US-funded station, Radio Peace, since it opened after the fall of the Taleban in 2001.

The BBC's Charles Haviland in Kabul says that at times Ms Zaki criticised the former mujahideen, some of who have been implicated in war crimes.

Observers say that the motive behind the murder is far from clear, and a massive police operation is now underway to identify and arrest the killers.

'Freedom of expression'

Zakia Zaki started her radio career eight years ago. At the time Parvan province was one of the few areas in the country to be controlled by anti-Taleban forces.

The Independent Association of Afghan Journalists has condemned the murder, describing it as an example of how difficult the working environment has become for journalists and especially for women.

"She believed in freedom of expression, that's why she was killed," the association's head Rahimullah Samander told Reuters.

The group said she had received threats in the past but had no personal enemies.

The killing comes six days after the shooting dead of another Afghan woman working in journalism, a 22-year-old newsreader from a private television station, Shakiba Sanga Amaj.

According to senior police sources in Kabul, her father has blamed two male relatives and one person has been arrested.