Hong Kong's leader on Monday announced she had postponed a policy speech after being ordered to travel to mainland China for meetings with central government officials.

Chief executive Carrie Lam had been due to make a key annual address on Wednesday outlining her administration's plans for the politically restless city.

But the speech clashed with a sudden announcement that Chinese President Xi Jinping would make a visit that day to the neighbouring mainland city of Shenzhen.

Lam said she would also travel to Shenzhen, which is celebrating its 40th anniversary as a special economic trade zone, ahead of a visit to Beijing later in the month.

Her speech, she added, would now be delivered in late November.

"The best way forward is for the chief executive to go to Beijing and personally explain why these measures are important for Hong Kong," Lam said of the speech.

Hong Kong is ruled under a "One Country, Two Systems" model that allows it to retain a degree of autonomy and some freedoms that are denied to citizens on the authoritarian mainland.

But last year's huge and often violent pro-democracy protests prompted Beijing to ramp up control over a city it now sees as a national security threat.

In June it imposed a sweeping new security law on the restless hub which criminalised a range of political offences.

Hong Kong's Chief Executive Carrie Lam was originally due to make an annual policy speech on Wednesday
Hong Kong's Chief Executive Carrie Lam was originally due to make an annual policy speech on Wednesday AFP / ISAAC LAWRENCE

It also allowed mainland security agents to operate openly in the city for the first time, as well as grant Beijing jurisdiction over especially serious cases.

The Chinese government has thrown its full support behind Lam, a pro-Beijing appointee, despite her dismal approval ratings.

Millions hit the streets last year for seven straight months of protests calling for greater freedoms and police accountability.

Both Beijing and Lam have rejected those demands and dismissed the unrest as part of a foreign plot.

Businesses in the city would have watched Lam's speech this week closely.

The national security law and deteriorating US-China relations have raised doubts over Hong Kong's future as a regional trading powerhouse, with the city mired in a recession even before the coronavirus outbreak.

A lack of affordable housing in what is one of the world's most expensive cities has also helped fuel resentment towards Beijing.

Mass arrests and an anti-coronavirus ban on public gatherings have largely kept a lid on protests this year.

But residents remain deeply polarised, with no reconciliation measures yet unveiled to bridge the divide.