STORY: Hundreds of workers joined protests at Foxconn's major iPhone plant in China Wednesday (November 23).

The Zhengzhou site has come to represent a build-up of frustrations with the country's ultra-harsh health crisis rules.

The trigger for the protests - which began early Wednesday (November 23) - appeared to be a plan to delay bonus payments.

That was according to many of the demonstrators on livestream feeds, in videos which could not be immediately verified by Reuters.

Some workers surrounded by people in full hazmat suits chanted 'give us our pay'.

Other footage showed workers taking down quarantine barriers and smashing surveillance cameras.

Many of the problems have emerged since Foxconn imposed a so-called closed loop system in October.

This sees operations staff live and work on-site, isolated from the wider world.

It has sparked anger about strict quarantine rules, the company's inability to stamp out outbreaks and poor conditions.

Former workers have estimated that thousands have fled the factory campus.

Before the unrest, the Zhengzhou plant employed some 200,000 people.

To retain staff and lure more workers Foxconn has had to offer bonuses and higher salaries.

The firm said Wednesday it would communicate with employees and the government to avoid violent incidents from happening again.

Foxconn is Apple's biggest iPhone maker, accounting for 70% of global shipments.