Updated

A contentious election in which Cambodia's ruling party extended its long-running majority but the opposition made impressive gains could lead to parliamentary paralysis.

Prime Minister Hun Sen's Cambodian People's Party claimed 68 of the National Assembly's 123 seats in Sunday's polls, with the remaining 55 going to the opposition Cambodia National Rescue Party.

However, opposition leader Sam Rainsy on Monday rejected the provisional results, calling for an independent investigation into allegations that as many as a million people may have been deprived of their right to vote.

The constitution says a quorum of 120 assembly members is needed to open a parliamentary session, raising the possibility that an opposition boycott could leave the country without a fully functioning government.