Honour killings have been rampant in orthodox and socially backward groups in many countries including India, Bangladesh, Pakistan, Turkey, Jordan and the Palestinian Territories, they say.
While statistics are hard to come by due to non-reporting of such crimes, United Nations Population Fund approximates that as many as 5,000 women are murdered in this manner each year around the world.
But this is undoubtedly a low estimate, as reports from many countries are filtered and not brought to public notice.
According to Amnesty International, honour killings are the most widespread in Pakistan. A recent report by the Human Rights Commission of Pakistan (HRCP) states that 647 women were killed in the name of "honour" in 2009 -- up by 13 per cent from 2008 when 574 such killings were reported.
"An honour killing is carried out because the honour of men in the family is perceived to have been injured," I A Rehman, secretary-general of HRCP, was quoted as saying.
"This is basically a consequence of the low status of women in society," Rehman said.
Such crimes are committed for a wide range of "offences" -- marital infidelity, pre-marital sex, flirting, or even failing to serve a meal on time that can be perceived as impugning the family honour.
In one such case, a husband murdered his wife based on a dream that she had betrayed him, according to the Amnesty International. In Turkey, a young woman's throat was slit in the town square because a love ballad had been dedicated to her over the radio.
A June 2008 report by Turkey's Human Rights Directorate says that in Istanbul alone, there is one honour killing every week and over 1,000 were killed during the last five years.
In the Gaza Strip and the West Bank, it is believed that three-four women are killed every month in the name of saving honour. The Palestinian Authority follows the Jordanian law, which gives men reduced punishment for killing wives or female relatives if they have brought dishonour to the family.
Similarly, Article 548 of Syria's Penal Code states that if a person catches his wife or sister "committing adultery (called flagrante delicto) or illegitimate sexual acts with another and if he kills or injures one or both of them", he should benefit from a reduced penalty which should not be less than two years in prison.
In Morocco, Article 418 of Penal Code grants "extenuating circumstances" to a husband who murders or injures his wife for "flagrante delicto". About 200 women are killed each year in such fashion in the country, as per private estimates.
According to IRIN, the news branch of the UN's Office for the Coordination of Humanitarian Affairs, as many as 133 women were killed in the Iraqi city of Basra alone in 2006 -- of them 47 were honour killings and 79 for violation of "Islamic teachings".
Honour killings are not restricted to the Middle East or South Asia only. Developed countries such as the US, Britain, Canada, Germany, Sweden and other parts of Europe have also witnessed such crimes.
It is thought that up to 12 honour killings happen every year in the UK which usually occur within South Asian and Middle Eastern families. In December 2009, London Metropolitan Police reported that there had been a huge rise in such crimes and they have recorded 211 such incidents in the year.
Last year, the father and brother of a teenage girl, Aqsa Parvez, were sentenced to life in Canada for killing her in 2007. Parvez's crime was that she wanted to wear western clothes and get a part-time job like her Canadian peers. There have been 13 such cases in the country since 2002.
This highlights the fact that even in the West, young women, and sometimes men, are not safe from such bloody reprisals for defying the strict family code.
In India, honour killing is most prevalent in states such as Punjab, Haryana, western areas of Uttar Pradesh and in some parts of Bihar. In many instances, khap panchayats or caste councils order the killings for marrying against their wishes.
But the back-to-back cases in the national capital and elsewhere in the country in the past one month have shaken the conscience of modern India.
According to a new analysis by NGO Shakti Vahini, such sordid incidents have been reported from all over the country and in 90 per cent of the cases, the perpetrators of the crime were from the girl's family.
The study, commissioned by National Commission for Women (NCW), also found that 72 per cent of the 326 cases documented over the past one year involved couples that entered into inter-caste marriages.
Meanwhile, the Government has announced setting up of a Group of Ministers (GoM) that will consider amendments to the law to deal with the issue. An amendment bill, expected to be tabled in Parliament in upcoming monsoon session, proposes to include a clause under Section 300 of the Indian Penal Code to deal exclusively with honour killings