* First time protesters have targeted famous party district
* Police warn of safety risks from banned march
* Data set to show recession as central banks cuts rates
* Pompeo says China trampling on rights in Hong Kong (Adds details on security measures, background)
HONG KONG, Oct 31 (Reuters) - Hong Kong police tightened security and braced for potential evening clashes on Thursday between masked "Halloween" pro-democracy protesters and fancy-dressed clubbers in a popular party district in the heart of the city.
Protesters, many of whom still wear now-illegal face masks, are planning to march from Victoria Park in the Causeway Bay shopping district to the Lan Kwai Fong bar and entertainment area near Central.
The area is popular with office workers and party-goers including expatriates, who often pack its narrow streets.
Police have banned the march and said they would close roads including the sloping Lan Kwai Fong strip itself, from early afternoon until Friday morning to "facilitate the public celebrating." It was not immediately clear how that would work.
It is the first time protesters have targeted the party district in five months of increasingly violent, anti-government unrest.
Police, who have been warning for days of the threat to public order and safety from the event, are planning to deploy 3,000 riot officers and three water cannons outside government offices near the route, according to media.
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.
China denies meddling and has accused foreign governments, including the United States and Britain, of stirring up trouble.
U.S. Secretary of State Mike Pompeo said on Wednesday that China was "trampling (on) the most basic human rights of its own citizens".
"We have seen this in Hong Kong, where they need to live up to their promises and commitments," Pompeo said.
Some protesters have thrown petrol bombs at police, lit fires across the Asian financial hub and trashed buildings during recent demonstrations.
Police typically fire at protesters with tear gas and water cannon. Bar owners told Reuters that the police pledged to take a low profile on the fringes of the celebrations, and to protect them.
Typically, weekends and special events like Halloween see hordes of revellers spill out of the bars and clubs in Lan Kwai Fong. A stampede at midnight on New Year's Eve in 1992, when thousands had gathered, killed at least 20 and wounded scores.
Paulo Estaban, manager of Ciao Chow, a restaurant in the heart of the strip, said the protests were not a "big concern" and that they would be "running business as usual". Many others agreed.
But one manager of a top-end, high-rise bar, who did not want to be identified, said it would be "madness" not to be worried.
Hong Kong's subway operator MTR Corp said it would shut some stations earlier than usual after conducting a 'joint risk assessment' with the government. Central station, a few minutes walk from the thronging district, will shut by 9 pm (1300 GMT).
Prince Edward station, on the bustling Kowloon peninsula, would be shut from 2 pm as protesters planned a vigil to mark two months since large clashes between police and protesters.
The city's local theme park, Ocean Park, said it was cancelling its annual Halloween fest to prioritise the safety of visitors and staff.
Staff at the park, which is located on the southern part of Hong Kong island and away from the teeming bars, expressed disappointment at the last minute cancellation.
This month Hong Kong leader Carrie Lam banned protesters from wearing face masks under a British colonial-era emergency law, but the measure has been largely ignored.
Halloween masks have not been banned, which would make it difficult for police to differentiate protesters from the plethora of revellers in fancy dress.
Economic data due later on Thursday is set to show that Hong Kong has slid into its first recession since the 2008 global financial crisis as the protests, trade tensions and global pressures weigh. Its central bank also cut rates on Thursday in step with the U.S. Federal Reserve.
Pressed on government plans to relieve the hit to businesses in Hong Kong from the protests, chief executive Carrie Lam told a conference the circumstances warranted "exceptional" measures.
"If we still act in the same conventional mode as if business is usual and life is normal, then we are not being very responsible...we are facing some exceptional times that call for some exceptional responses from the government," Lam said.
Her administration has pledged around HK$21 billion ($2.68 billion) of financial aid for business since August, from rent to fuel subsidies. (Reporting by Nick Macfie, Twinnie Siu, Jessie Pang and Tom Westbrook; Writing by Farah Master and John Geddie; Editing by James Pomfret and Kim Coghill)