Authorities in Pakistan's most populous province on Saturday banned an outdated medical procedure in which rape victims are subjected to an invasive physical examination.

The move comes after critics of the "two-finger test" this year sued the government of Punjab province, home to about 110 million people, in a bid to stop the practice dating back to the time of British colonial rule.

Proponents of the internal examination claim it can assess a woman's sexual promiscuity and her "honour", and whether she had been "habituated to sexual intercourse".

Backlash to the test has been growing in recent years, with critics saying it provides zero useful information and is traumatic for rape victims.

Punjab health authorities in September admitted the test held "limited evidentiary value" but the practice continued.

Saturday's ban, which takes immediate effect across Punjab, effectively preempts the ongoing court case.

A similar case is also underway in the southern province of Sindh with momentum growing for a nationwide ban.

Welcoming Punjab's ban, Sidra Humayun, a case manager for survivors of sexual and gender-based violence, told AFP it would be a challenge to ensure compliance by medical workers.

The mentality that still "links the reliability of a rape victim's claims to her virtue and honour" in legal cases also must be addressed, she added.

The World Health Organization has declared the test "unscientific, medically unnecessary and unreliable".

Neighbouring India banned the two-finger test in 2013 and Bangladesh followed suit in 2018.

Sameer Khosa, the lawyer behind Punjab's court petition, welcomed the ban but said other problematic practices such as virginity testing through the examination of the hymen are still being performed.

Pakistan is a deeply conservative and patriarchal nation where victims of sexual abuse often are too afraid to speak out, or where police frequently fail to investigate cases seriously.