The man was arrested from his residence in Bihar. (Representational)

A 28-year-old man was arrested Monday for allegedly killing his in-laws in Uttar Pradesh's Kushinagar district, police said.

Mantu Gupta killed his father-in-law Chhangur Gupta (60) and mother-in-law Kismati Gupta (55) during their sleep with a sharp-edged weapon in Khangi Bazaar area under Barwapatti police station on Sunday night, Superintendent of Police Rajeev Narayan Mishra said.

The couple's grandson couple Aditya, 14, suffered injuries in the incident, SP Mishra said, adding the boy was presently receiving treatment at a hospital.

Mantu was arrested from his residence in Bihar and, during questioning, he confessed to have committed the crime, the SP said.

"Mantu suspected his wife's fidelity. He had complained regarding this to his in-laws," he said.

The accused's wife Shanti said since marriage in 2018 Mantu had been harassing her for dowry, the SP said.