HONG KONG (Reuters) - Thousands of Hong Kong pro-democracy protesters, many of whom still wear now-banned face-masks, plan to combine with fancy-dress clubbers on Thursday in the party district of Lan Kwai Fong on a potentially dangerous and rowdy Halloween.

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The protesters say they will march, without police permission, from a park in the Causeway Bay shopping district through the heaving bar streets of Wan Chai to the steep, narrow foothills of the Peak above Central.

Every weekend, office-goers and clubbers spill out of the Lan Kwai Fong bars on to the streets, even without the additional presence of protesters who have thrown petrol bombs at police, set fires and trashed buildings during five months of unrest.

A stampede at midnight on New Year’s Eve in 1992, when thousands had gathered, killed at least 20 and wounded scores.

This month Hong Kong leader Carrie Lam banned protesters from wearing face masks under a resuscitated British colonial-era emergency law, but few have taken any notice.

Halloween masks have not been banned, which will make it difficult for police - who have responded to the violence with tear gas, rubber bullets and water cannon - to identify protesters.

Police said they would close some roads, including the short, L-shaped Lan Kwai Fong itself, from early afternoon on Thursday until the next morning “to facilitate the public celebrating”. It was not immediately clear how that would work.

“Based on past experience, such unauthorized assembly will impose serious threat to public order and public safety,” police said in a statement.

“Members of the public should avoid traveling to the concerned area when public disorder occurs.”

Protesters are angry at what they see as Beijing’s increasing interference in Hong Kong, which returned from British to Chinese rule in 1997 under a “one country, two systems” formula intended to guarantee freedoms not seen on the mainland. Some are increasingly focusing their fury on mainland Chinese in the city.

China denies meddling and has accused foreign governments, including the United States and Britain, of stirring up trouble.

Lam said she expected negative economic growth in the Asian financial hub this year, in part as a result of the unrest.

“The increasingly violent reality since June is hurting Hong Kong’s economy,” Lam said in a speech on Wednesday. “...what started off as peaceful protests, a hallmark of Hong Kong’s rights and freedoms, have turned into violent acts by rioters.”

With visitors deterred by months of violence, many small firms across the city have already closed or are struggling to turn a profit.

Lam’s made her gloomy forecast two days after Financial Secretary Paul Chan said Hong Kong had slipped into a technical recession, meaning two successive quarters of contraction. That is expected to be confirmed by Thursday’s third-quarter GDP data.

The protests, which started over an extradition bill that has now been withdrawn, have plunged the city into its biggest crisis in decades and pose the biggest populist challenge to Chinese President Xi Jinping since he came to power in 2012.