Hong Kong's democracy protesters are considering travelling to Beijing to directly petition Communist authorities as the Chinese capital hosts US President Barack Obama and other world leaders at an upcoming summit.

The protesters have held continuous street rallies for a month, demanding free leadership elections for the semi-autonomous city in 2017.

Beijing has refused to back down on its insistence made on August 31 that candidates in the vote must be vetted by a loyalist committee, a decision critics say is designed to ensure the election of a pro-Beijing stooge.

Alex Chow, head of Hong Kong's main student union which has been at the vanguard of the protests, said demonstrators were considering upping the ante by attempting to travel to Beijing and press authorities for direct talks.

"We should tell the world and the government... that the decision made on August 31 must be rescinded," Chow told demonstrators at the main protest site late Thursday, urging them to think about "directly approaching Beijing".

Protesters are apparently considering whether to attempt to crash the Asia-Pacific Economic Cooperation (APEC) forum in Beijing on November 10-11, when Chinese President Xi Jinping will host leaders from the United States, Russia and Japan among others.

But it is not clear whether student leaders, who have become well known through their speeches and media appearances, would be allowed to travel to the capital.

Hong Kong citizens may travel freely into China as long as they have travel permits issued by mainland authorities, but border officials can deny their entry -- a tactic that has been used to keep critics of Beijing out in the past.

"If we can't go through customs then Beijing is sending a message that they do not care about Hong Kongers' views about the NPC (National People's Congress) decision and the direction of constitutional development," Chow said.

Demonstrators remain encamped on three of Hong Kong's major thoroughfares, but are under pressure to keep up the momentum in their campaign.

The crowds, which numbered in their tens of thousands at the beginning of the month, have sharply dwindled. Hong Kong's authorities appear to be pursuing a strategy of attempting to tire them out, rather than clearing them by force.