An explosion in southern Gaza has torn through a party attended by relatives of the West Bank-based Fatah strongman Muhammad Dahlan, injuring 50 people.

The blast happened on Tuesday at a wedding reception in Khan Younis.

The groom, who is Mr Dahlan's nephew, as well as women and children, were injured. The Hamas authorities said three suspects were in custody.

The device was reported to have been placed under a street stage erected so the wedding guests could dance.

Muhammad Dahlan is widely hated by the Hamas faction because of actions he took against it in his former role as head of Fatah's powerful security force.

Mr Dahlan, a native of the Gaza Strip, left the Palestinian territory in June 2007, as pro-Hamas forces ousted the Fatah-dominated Palestinian Authority.

A spokesman for Hamas, Ihab al-Ghussein, said initial investigations suggested that the explosive device which caused the blast was what he called a "sound bomb".

Five of the guests were in a critical condition in hospital, Agence France Presse reported.