Newly elected Hong Kong pro-democracy lawmakers have thumbed their noses at Beijing at a swearing-in ceremony to start the legislative session.

They displayed flags declaring that Hong Kong is not a part of China and called out for "democratic self-determination" for the semiautonomous Chinese city at Wednesday's oath taking session.

The antics foreshadow what's expected to be a chaotic term for Hong Kong's legislature after a group of grassroots activists were elected in September, adding to the opposition's numbers in the semi-democratic Legislative Council.

One lawmaker recited the oath very slowly while others mispronounced the word China.

Some lawmakers who tried to modify the oath were admonished by the clerk, who refused to swear in three because they changed the wording.