Gunmen on motorbike shot dead a women's rights activist and her brother north of Afghanistan's capital Thursday, officials said, as a wave of assassinations ravages the violence-wracked country.

Freshta Kohistani, aged 29, was the second activist to be killed in two days after a prominent pro-democracy advocate was gunned down in Kabul on Wednesday.

Their murders follow a similar pattern seen in recent weeks, in which prominent Afghans have died in targeted killings in broad daylight, several of them in the capital.

-Unknown gunmen on motorbike assassinated Freshta Kohistani in Kohistan district of Kapisa province- interior ministry spokesman Tariq Arian told reporters.

Kapisa provincial governor Abdul Latif Murad told AFP that the shooting had taken place near Kohistani's home and that her brother was also killed in the attack.

Kohistani had enjoyed a relatively large following on social media, and regularly organized civil society events in Kabul calling for women's rights. She was married and had one child.

Days before her death, she wrote on Facebook that she had asked for protection from the authorities after receiving threats.

She had also condemned the ongoing wave of assassinations of journalists and other prominent figures.

-Afghanistan is not a place to live in. There is no hope for peace. Tell the tailor to take your measurement, tomorrow it could be your turn- she tweeted in November.

Journalists, politicians and rights activists have increasingly been targeted as violence surges in Afghanistan, despite peace talks between the government and the Taliban.

On Wednesday, Mohammad Yousuf Rasheed, who led an independent election monitoring organisation, was ambushed and shot in morning rush-hour traffic in Kabul along with his driver.

His murder came a day after five people -- including two doctors working for a prison on the outskirts of Kabul -- were killed by a car bomb.

A prominent Afghan journalist was also shot this week while on his way to a mosque in the eastern city of Ghazni.

Rahmatullah Nekzad was the fourth journalist to be killed in Afghanistan in the last two months, and the seventh media worker this year, according to the Kabul-based Afghan Journalists Safety Committee.