Hong Kong's pro-democracy camp failed on Monday to regain some veto power in the city's legislature in a pivotal by-election, struggling to draw what they hoped would be protest votes against creeping control from Communist Party rulers in Beijing.

The democrats won only two of four seats up for grabs, with the opposition now left one seat short from having the power to block most bills in the 70-seat legislative chamber.

The by-election marked the first time the democratic camp has lost its long standing veto power via the ballot box, raising fresh questions over the future of the struggle for democracy and autonomy in the freest city in greater China.