Cambodian police have arrested three men suspected of beating up two opposition lawmakers during an assault outside of the National Assembly last week.

The Interior Ministry said the men turned themselves in to police Tuesday and confessed to the attack that occurred at a pro-government protest outside the assembly on Oct. 26.

In a statement, the ministry gave few details about the men who are believed to be supporters of Prime Minister Hun Sen's ruling party.

International human rights groups have demanded an independent investigation into the beatings of the opposition lawmakers, Nhoy Chamreoun and Kong Sakphea. The lawmakers were pulled from separate cars and beaten after leaving a session of the assembly. One was knocked temporarily unconscious and other was seen with a bloodied nose.