HONG KONG — Huge crowds of protesters thronged the streets of Hong Kong on Sunday afternoon, hours after President Hu Jintao of China swore in a new chief executive and cabinet for the territory.

Surging down broad avenues between high-rises in a central shopping district, the protesters marched toward two government office complexes carrying a variety of banners. A wide range of causes were represented, including greater democracy in Hong Kong and calls for better state pensions and day care.

But the most common theme was derision toward Hong Kong’s new chief executive, Leung Chun-ying. Democracy activists contend that he is “a wolf in sheep’s clothing,” whose sympathies for the Chinese Communist Party may lead him to roll back some of the city’s cherished civil liberties — although Mr. Leung has denied that.

“We worry that as he becomes our leader, he will betray our freedoms and civil rights,” said Juno Wu, 24, a librarian.