Thousands of pro-democracy protesters took to the streets of Hong Kong Sunday for the first time since mass demonstrations shut down parts of the city for more than two months.

A sea of yellow umbrellas -- the symbol of the campaign -- moved slowly through central Hong Kong with crowds shouting for "true universal suffrage".

But numbers were well below expectations with 13,000 attending according to organisers -- just over a quarter of the 50,000 they had hoped for.

"Today's protest wasn't a small one. It was smaller than we expected, but it's wrong to say Hong Kongers have given in to fake democracy," said organiser Daisy Chan.

Police said up to 8,800 people had joined the march, a fraction of the tens of thousands who gathered at the peak of the protests.

Authorities have made no concessions to activists' demands and tensions remain high in the semi-autonomous Chinese territory.

Police warned ahead of the rally that demonstrators were likely to once again try to occupy some of Hong Kong's main roads, which were cleared of tented camps in December.

But by late afternoon the march remained peaceful, with no sign that the crowds -- including many people carrying yellow balloons -- planned to take back the streets.

"We don't have a plan (to reoccupy). If others want to do it, they will have to do it themselves," student leader Alex Chow told AFP.

Despite the disappointing turnout, there was a sense of determination among demonstrators.

"We just want to express our frustration with the government in Hong Kong," said protester Ronnie Chan, who is in his 40s and works in sales and marketing.

"We understand there is very little we can do, but if we don't speak out nothing will change."

The pro-democracy rallies drew around 100,000 at their height and saw intermittent violent clashes with police, but public support faded as the weeks dragged by.

- 'Tired of politics' -

China has promised Hong Kongers the right for the first time to vote for their next chief executive in 2017. But it ruled that nominees must be vetted by a pro-Beijing committee, a proposal which has been heavily criticised by activists.

The founders of the pro-democracy movement including Benny Tai, along with teenage activist Joshua Wong and other student leaders, urged residents to keep fighting as they joined Sunday's rally.

"If we don't dream, we don't have hope. We should persist then we will succeed," said Tai.

Wong warned against accepting universal suffrage within the restrictions of Beijing's framework.

"I hope people understand that if we take that now, it will be forever," he said.

But political analyst Sonny Lo said residents were exhausted from protests over political reform.

"At this moment, members of the public are tired of politics. The democrats have to strategise very carefully," said Lo, head of the social sciences department at the Hong Kong Institute of Education.

Hong Kong's government is urging the public to support Beijing's electoral plan, which needs the backing of two-thirds of the city's legislature to be passed.

Lam Woon-kwong, convenor of the Executive Council or cabinet, warned campaigners to accept Beijing's offer.

"You can't threaten the central authorities," he told a radio programme Sunday.

"If we can have consensus to have universal suffrage in 2017 first and democratise further later, it would be a more pragmatic approach."

But for some protesters, backing down is not an option.

"I'm just doing my bit. Some people may have compromised, but I definitely will not," said one father of two who gave his name as Alvin.

Protests in Hong Kong pre-date the Occupy movement -- last July hundreds of thousands demonstrated a month before Beijing ruled on political reform.