Hong Kong goes to the polls Sunday in an election which for the first time sees young independence activists calling for a complete break from China running for office.

It comes as some in the semi-autonomous city grow increasingly concerned that Beijing is tightening its grip in a range of areas, from politics to media and education.

The vote for members of the Legislative Council -- Hong Kong's lawmaking body -- is the most important poll since major pro-democracy rallies brought parts of the city to a standstill in 2014, calling for political reforms.

When the months-long protests failed to win concessions from Beijing, a new "localist" movement emerged, seeking far more distance from the mainland.

Now some young campaigners are demanding outright independence, others the chance for Hong Kong to determine its own future in a referendum.

The more strident independence activists -- slammed by Beijing and Hong Kong authorities as acting illegally by promoting the breakaway -- have been banned from running in Sunday's election, a move which sparked outrage over political censorship.

Victory for the handful who are standing would be a massive coup for the nascent movement, and polls predict some will win seats.

But with their numbers still small, it would not tip the balance of a legislature whose framework is skewed towards the establishment.

The election is only partially democratic and it is almost impossible for the anti-Beijing camp ever to gain a majority.

While 40 of the Legislative Council's 70 members will be directly elected by the public on Sunday, 30 will be selected by small voting blocs from special interest groups representing a range of businesses and social sectors. Those seats always go predominantly to pro-Beijing candidates.

What the pro-democracy camp wants to ensure is that it holds on to enough seats to block important bills, which need to be voted by a two thirds majority.

The loss of just four seats would mean that veto power slips away, leaving a legislature where the odds are stacked even more in Beijing's favour.

The momentum behind new young activists could draw support away from more established pro-democracy parties, splitting the vote.

On the eve of the election, five democrats dropped out of campaigning in a bid to consolidate voting behind those candidates with the best chance of winning.

As divisions become increasingly entrenched, wrangling between the pro-establishment and democracy camps has led to a Legislative Council often hamstrung by filibustering and point-scoring.

In a city where poor housing and low salaries are serious concerns, many frustrated residents say it is now time to put politics aside and focus on struggling communities.