In what appears to be a case of honour killing, two brothers beheaded their 17-year-old sister for having an affair with her cousin.

The incident took place in the presence of several people in Bahmani village in Uttar Pradesh's Shahjahanpur district on Monday evening.

After beheading Phool Jahan outside the house of the cousin, Mohammad Achchan, the brothers Gul Hasan, 25, and Nanhe Mian, 20, paraded her head around the village for about an hour and said that they do not regret killing her. 

"We cannot allow our daughters or sisters to do an affair. Whatever we did is to give a lesson to the people to be alert about any such happening in their families. No girl should dare to repeat such an act in the area. We have no regrets for whatever we did," Nanhe Mian said, according to an eyewitness, reports India Today

While parading Phool Jahan's severed head, the brothers had claimed they would surrender but escaped later.

The incident took place under Paraura police station. Superintendent of Police Bablu Kumar said they will arrest the siblings soon. "Force has been deployed in the village," he said.

Phool Jahan had once expressed her desire to marry Mohammad Achchan but her brothers had raised objection to it. They had even warned her to stay away from Achchan, The Times of India reports.

But when the brothers found out that she was still in touch with Achchan and allegedly spent a night with him, they dragged her out and beheaded her in front of the villagers.