An eight-year-old boy has been killed after a grenade was thrown into a flat where he was sleeping.

The victim, believed to be from Birmingham, had been visiting relatives with his mother, brother and sister in the Swedish suburb Biskopsgården, near Gothenburg, the Birmingham Mail reports.

Police said an unidentified attacker threw the hand grenade through a window as part of a suspected underworld feud.

At least five children and several adults are believed to have been in the residence at the time of the attack.

Gothenburg police spokesman Thomas Fuxborg, told local media that the boy's death is being investigated as murder.

"Someone was standing outside the apartment and threw a hand grenade through the window, into the living room," he told Thelocal.se.

"The boy was not part of the family registered at the address. This is abhorrent.

"From the outside it is impossible to know who is in the apartment. That it affects an eight-year-old completely innocent boy, is despicable."

ITV News has contacted the Foreign Office for a statement.