Two well-known Bangladeshi television journalists have been killed in the capital, Dhaka.

Sagar Sarwar and his wife, Meherun Runi, both in their late 30s, were stabbed to death at their apartment early on Saturday.

Their bodies were found by their five-year-old son, who then called relatives living nearby, police said.

The motive for the killings was not known and it was unclear if the deaths were related to their work.

Mr Sarwar, a news editor at private TV station Maasranga, was found with his hands tied behind his back.

His wife worked as a senior reporter at ATN Bangla, another private station.

Preliminary investigations suggested that the killings had been planned and that the couple had probably known their attackers, a senior detective was quoted by local newspapers as saying.