ISLAMABAD • Pakistan has passed long-awaited legislation closing a loophole that allowed people who killed for "honour" to walk free, three months after the murder of a social media star by her brother sparked international revulsion.

The legislation, passed unanimously by the National Assembly on Thursday, mandates life imprisonment even if the victim's relatives forgive the murderer.

The assembly also passed a Bill increasing the punishments for some rape offences, mandating DNA testing and making the rape of minors or people with disabilities punishable by life imprisonment or death.

Women have long been fighting for their rights in Pakistan, where so-called "honour" killings claim the lives of hundreds each year.

Rape conviction rates are close to zero per cent, largely due to the law's reliance on circumstantial evidence and a lack of forensic testing.

Rights groups and politicians have, for years, called for tougher laws to tackle perpetrators of violence against women.

The gruesome murder of Facebook star Qandeel Baloch in July catapulted the issue into the international spotlight.

"This is a step in the right direction," women's activist and columnist Aisha Sarwari said.

But rights activist Farzana Bari was more cautious, saying the Bill still allowed a judge to decide whether a murder qualified as an "honour killing" or not.

Prime Minister Nawaz Sharif later issued a statement hailing the passage of the Bill and vowed police and courts would implement it.

"We will make... sure to fully enforce this legislation across the country," a statement issued by his office said.

"Women are the most essential part of our society and I believe in their empowerment, protection and emancipation."

The perpetrators of honour killings - in which the victim, normally a woman, is killed by a relative on the pretext of defending family "honour" - often walk free because they can seek forgiveness for the crime from another family member.

A 2005 amendment to the law pertaining to honour killings prevented a man who kills a female relative from pardoning himself by saying he is the "successor" of the victim and, therefore, does not need to seek pardon from other relatives.

But punishment was left to a judge's discretion when other relatives of the victim forgive the killer - a loophole which critics say had been exploited.

The amendments, passed on Thursday and published on the National Assembly website, mandate judges to sentence someone who kills in the name of "honour" to life imprisonment, even if he has been forgiven and, thereby, can avoid the death penalty, said senior opposition lawmaker Farhatullah Babar.

The amendments regarding rape, in addition to calling for DNA tests and toughening the punishment in some cases, also protect a victim's identity and mandate that cases be brought to court within three months.

Ms Sharmeen Obaid-Chinoy, whose documentary on honour killings won an Oscar this year, posted on Twitter: "Thank you to PM Nawaz Sharif for keeping his promise."

The death of social media star Baloch, judged by many in the country as infamous for selfies and videos that by Western standards would appear tame, reignited polarising calls for action after her brother admitted killing her.

AGENCE FRANCE-PRESSE, REUTERS