Almost 5,000 people marched through Hong Kong on New Year's Day in protest against the government's attempt to disqualify four pro-democracy lawmakers, according to a police estimate.

Hong Kong's semi-autonomous government has started legal proceedings against four recently elected legislators, who altered their swearing-in oaths to stage a protest against the Chinese government in Beijing.

Their demonstration included flaunting a banner that read "Hong Kong is not China", which used language that some have claimed was derogatory Japanese slang.

The legislators belong to Youngspiration, a burgeoning political party that challenges Beijing's interference in Hong Kong's affairs.

The party's stated aim is a referendum on Hong Kong's right to self-determination in 2020.

Protesters waved flags reading "Hong Kong independence" and held placards in support of the foursome, according to Associated Press.

In November, the Hong Kong government won a similar challenge against two newly elected separatist lawmakers after Beijing said that anyone who doesn't properly take their oath should be barred from office.

Beijing's intervention has fueled growing concern among many Hong Kong citizens that China's government is eroding the city's wide autonomy.

Residents are anxious about future governance of the region; the constitutional principle of "one country, two systems" is set to expire in 2047.