Hong Kong students and teachers protested Tuesday for a sixth straight day against plans to introduce Chinese patriotism classes, as political tensions rise days ahead of legislative polls.

Protesters at the government headquarters said they would not vote for parties that supported "national education", which they say is a bid to brainwash children with Chinese Communist Party propaganda.

"I feel national education is an important issue because it could affect many generations of children's education," second year university student Cheung Nga-lam said at the demonstration, which began on Thursday.

"The new Legislative Council members will definitely have an influence on the issue because whatever they say affects society."

The former British colony goes to the polls on Sunday to elect a new 70-seat legislature, but power will continue to reside with the pro-Beijing executive appointed by Chief Executive Leung Chun-ying.

Leung has ignored protesters' calls for a meeting and refused to abandon plans to implement the new education policy, which schools can adopt voluntarily from this week and will become compulsory by 2016.

"We are willing to talk to the anti-national education parties, but the prerequisite of the dialogue cannot be either to withdraw or not to withdraw," Leung told reporters.

Most schools have said they will not introduce the subject this year and want to see more details about how it should be taught.

The government says the curriculum is important in fostering a sense of national belonging and identity, amid rising anti-Beijing sentiment in the semi-autonomous southern city of seven million people.

But critics say the lessons extol the virtues of one-party rule and gloss over events like the bloody Tiananmen crackdown on pro-democracy protesters in 1989, and the mass starvation and extrajudicial killings of Mao's Cultural Revolution.

The protests have swelled in number from a few hundred in the mornings when students are in class, to several thousand at night. Up to 40,000 joined the rally on Saturday despite heavy rain, organisers said.

It was the second mass demonstration against the education policy in two months, after up to 90,000 people took to the streets in July.

A handful of students and teachers have gone on hunger strike to drive home their opposition to the plan. One woman was hospitalised on Tuesday after refusing to eat for several days.

There have also been calls for teachers and students to boycott classes.

"People are extremely interested in this issue so it is impossible for it to be discussed behind closed doors by a small representative body," said hunger striker Wong Hak-lim, a 56-year-old high school vice-principal.

Democratic Party lawmaker James To called on Leung to "immediately withdraw the package".

"It's my view that the government isn't genuine and really wants to brainwash children because they think the Hong Kong people aren't patriotic enough," he said at an election forum on Monday.

Hong Kong returned to Chinese rule in 1997 but maintains its own independent legal system which guarantees civil liberties not seen on the mainland.