Hong Kong's new Beijing-backed leader was sworn in yesterday amid rising discontent over widening inequality and lack of democracy in the semi-autonomous Chinese financial centre.

Tens of thousands of people took to the streets later in the day as part of annual protests when ordinary people air grievances.

Leung Chun-ying took office in an early-morning ceremony overseen by Chinese president Hu Jintao, becoming Hong Kong's third chief executive since British colonial rule ended and China regained control of the city 15 years ago.

There were clashes between demonstrators and police outside the convention centre where the event took place, and a demonstrator who tried to interrupt Mr Jintao as he spoke was bundled away by security officials.

Mr Leung, a 57-year-old police officer's son and self-made millionaire, takes over from career bureaucrat Donald Tsang amid swelling public anger about a yawning income gap, soaring property prices and rising unease about mainland China's growing influence on the region.

Mr Leung was chosen as chief executive in March, winning 689 votes from a 1200-seat committee of business bosses who mostly follow Beijing's wishes.

Hong Kong's electorate of 3.4 million, who can vote for neighbourhood councillors and half of all politicians, had no say.