ISLAMABAD: Prime Minister Nawaz Sharif on Thursday demanded “immediate action” over the brutal murder of a pregnant woman who was stoned to death outside the Lahore High Court while police stood by.

Farzana Parveen was attacked on Tuesday outside the LHC building in Lahore by more than two dozen brick-wielding attackers, including her brother and father, for marrying against the wishes of her family.

Hundreds of women are murdered by relatives in Pakistan each year supposedly to defend family “honour”, but the brazen nature of the attack, in broad daylight and in the centre of the country's second-largest city, has shocked rights activists.

The fact that police officers guarding the court apparently did nothing to intervene to save the 25-year-old has added to the outrage.

Prime Minister Sharif has told Punjab Chief Minister Shahbaz Sharif, who is also his brother, to act over the “brutal killing of the lady in the premises of the high court in the presence of police”, a statement from his office said.

“I am directing the Chief Minister to take immediate action and a report must be submitted by this evening to my office,” the premier said in the statement.

“This crime is totally unacceptable and must be dealt with in accordance with the law promptly.”

The prime minister often issues statements condemning bombings and terror attacks but it is unusual for him to comment on an individual murder.

Moreover, the LHC has also taken notice of the incident and has summoned a report on the matter from the district and sessions judge.

Parveen, who was three months pregnant, had gone to court to testify in defence of her husband Muhammad Iqbal — who was accused by her relatives of kidnapping her and forcing her into a marriage.

Iqbal, 45, told AFP that the couple had survived a previous attack during the first hearing of the case on May 12 and demanded justice for his wife.

He told the BBC that police officers at the court were “watching silently” while his wife was beaten to death on Tuesday, despite desperate attempts to get them to act.

“One of my relatives took off his clothes to catch their attention,” he told the broadcaster.

“A naked man was crying for help in front of the High Court but nobody intervened.”

The incident gained prompt attention from the global media and international human right activists reacted to it. The UN High Commissioner for Human Rights Navi Pillay strongly condemned the killing on Wednesday, urging the Pakistani government to take “urgent and strong measures” to put an end to so-called honour killings in the country.

British Foreign Secretary William described the murder as “barbaric” and urged the Pakistani government to fully investigate it.

“I am shocked and appalled by the death of Farzana Parveen: both for the appalling manner of her death, and the unspeakable cruelty and injustice of murdering a woman for exercising her basic right to choose who to love and marry,” Hague said in a statement.

“There is absolutely no honour in honour killings and I urge the government of Pakistan to do all in its power to eradicate this barbaric practice.

“I call on the Pakistani authorities to investigate this atrocious murder fully and bring those responsible to justice.”

Last year 869 women died in so-called “honour killings” according to the independent Human Rights Commission of Pakistan.

Conviction rates are very low due to Pakistan's blood-money laws which allow kin to forgive perpetrators, usually family members in such cases.