Pakistan's human rights commission says it has launched an investigation into the murder of the author, Fazal Wahab, whose work was critical of radical Islam.

The commission's chairman, Afrasiab Khattak, told the BBC he was extremely alarmed by the circumstances of Mr Wahab's murder on Tuesday.

Mr Wahab, an outspoken critic of radical Islamic clerics, was shot dead in the hill resort of Mingora, in North-West Frontier Province (NWFP).

The London-based human rights group, Amnesty International, too has expressed deep concern at the author's murder.

Pakistani police failed to give him any protection although he had complained that he was receiving death threats, Amnesty said in a report on Saturday.

The police have not taken any action to find his killers or protect his family from further attacks, the report added.

Islamist outrage

The human rights commission was most alarmed by the fact that Mr Wahab had told a press conference that he had received death threats, and yet received no extra security, Mr Khattak said.

Islamists have been very active in the province

Mr Wahab began receiving threats after clerics issued a "fatwa", or a religious ruling, against him.

Police say four armed men shot Mr Wahab dead while he was sitting in a shop in Mingora.

Mr Wahab is believed to have caused much local anger with his controversial writings.

His 2000 book Mullah ka Kirdar (The Mullah's Role) was banned amid angry protests.

Two years ago, local clerics issued a religious ruling declaring him a non-believer.

Last year, he published a book critical of Osama Bin Laden and his former Taleban hosts in Afghanistan.

No arrests

Islamists in NWFP and elsewhere in Pakistan have protested against the US-led "war against terrorism" since Pakistan decided to support that campaign in 2001.

The province is ruled by a six-party Islamist alliance which won elections in October on an anti-US platform pledging to enforce strict Islamic laws.

Mr Khattak said the new authorities were failing to make public security a prime responsibility. Instead, they were "creating terror for the civil society," he added.

In its report, Amnesty says the author's murder followed efforts by local authorities "to curtail the right of freedom of expression".

It said Mr Wahab's forthcoming book, Mullah ka Anjam (The Mullah's Fate) made "serious allegations of criminal activities against close relatives of local political leaders".

Local police say a murder case has been filed and an inquiry has begun but so far, no one has been arrested.