A pregnant woman and her husband have been abducted and shot dead by relatives who disapproved of their marriage, police said Sunday, the latest in a surge of reported "honour killings" in Pakistan.

The couple were murdered near the village of Thikriwala in Punjab province last Wednesday, senior local police official Malik Waris told AFP. The bodies were discovered after they washed up in a canal.

Waris said Aqsa Bibi, aged 22, and Shakeel Ahmed, 26, both worked at a local pharmacy and had got married in a court ceremony four years earlier.

Aqsa was expecting a child, though it was not immediately clear how many months' pregnant she was.

Their match enraged Aqsa's family, who lived in a nearby village.

Matters came to a head when one of her brothers, named as Muhammad Moavia, who had recently returned from abroad assembled a group of relatives to kidnap the couple.

They then shot them both in the head and dumped their bodies in the canal.

The accused remain at large, said Waris, adding that raids are underway.

Muhammad Azhar, another police official, confirmed the incident.

It was the latest in a string of "honour" killings, which are thought to claim around 1,000 lives every year in Pakistan.

Last week a man's throat was slit by relatives of his wife who disapproved of their match -- a rare instance of a male victim.

The week before, 16 year-old Zeenat Bibi was killed in Lahore by her mother for marrying a man of her own choice -- a case that sparked condemnation throughout the country.

Prime Minister Nawaz Sharif vowed to eradicate the "evil" of honour killings amid publicity for the Oscar-winning film on the subject, "A Girl in the River: The Price of Forgiveness".

As yet no fresh legislation has been tabled.