Pakistan honour killing
Pakistani human rights activists shout slogans during a demonstration in Lahore Arif Ali/AFP/Getty Images

Two teenage boys have been arrested in Pakistan after they confessed to having killed their mother and two step sisters in an honour killing attack.

The victims were slain in the eastern city of Lahore as they were accused of immoral behaviour and adultery.

The suspects slit the throats of all three victims when they returned home after visiting relatives in another city, local police said.

The men confessed during the initial investigation, saying they suspected that their stepsisters were involved in prostitution.

The triple murder followed an incident involving a young girl burnt alive by the man she had refused to marry.

The killing occurred in the eastern Punjab province last June, and was the second honour killing in the region in one week, after a young couple were hacked to death by her family for having married without their consent.

Honour killing is the murder of a person accused of bringing shame upon his or her family.

Out of the 5,000 honour killings that occur internationally each year, about 1,000 happen in India, and 1,000 take place in Pakistan, according to international digital resource centre Honour Based Violence Awareness (HBVA).

However, where the central criminal justice system is weak or unaffordable, honour killings may be ordered through informal legal systems. This makes the statistics unreliable, as the number of honour killings per year might be much higher than the official reports say.

The Human Rights Commission of Pakistan reported 943 women died in so-called honour killings last year.

Amnesty International reported 960 honour killings in Pakistan in 2010.

While India has seen some assertive legal action taken against honour killings, in Pakistan a culture of impunity remains. Police reports may be filed, but there is often little follow-up, particularly in rural areas, activists said.