The police have arrested the accused and his accomplice. (Representational)

A man was arrested in Thiruvananthapuram on Saturday for allegedly killing his 30-year-old girlfriend and burying her body in the backyard of his under-construction house, an official said.

Acting on a tip-off, police arrested Akhil, a prime accused in the case, from the Thiruvananthapuram International Airport, he said.

"We got information that he will reach the airport in the night. We were closely monitoring his movements. He is being interrogated and will be produced before the court tomorrow," the official told news agency PTI.

According to police, the couple were in a relationship for over six years. Problems arose when the woman came to know that he was marrying someone else.

Then Akhil and his brother hatched a conspiracy to kill his girlfriend. They strangulated her and buried the body in the backyard of their under-construction house, police said.

Police found the woman's decomposed body this week. They have arrested the accused and his accomplice.