Hong Kong: Several thousand pro-democracy protesters returned to the streets of Hong Kong on Sunday in the first large-scale rally since protests rocked the global financial hub late last year.

Some 2,000 police flanked an estimated 3,000 protesters marching on the city's glitzy shopping and financial districts, seeking to avoid a repeat of the so-called Occupy Central campaign that saw demonstrations shut down key roads for 2-1/2 months.

While organizers stood fast to earlier demands for full democracy in the former British colony, they insisted Sunday's marchers would be peaceful and not seek to occupy any sites.

"We want to make it clear to the government that ... we want true universal suffrage," said Daisy Chan, one of the organisers.

Other protesters feared they might face violence from anti-democracy groups later in the evening, and some were arming themselves with protective shields.

Many carried yellow umbrellas - a symbol of last year's campaign after protesters used them to fend off police pepper spray attacks.

Hong Kong returned to Chinese rule in 1997 and enjoys wide-ranging freedoms under a so-called "one country two systems" arrangement. Beijing has allowed elections for choosing the next chief executive, but wants to screen candidates first.

The situation is being closely watched internationally, a reflection of Hong Kong traditional importance as a free commercial centre and port.