Man arrested for threatening New Year's Eve in Sydney

Counter-terrorism police have arrested a man in Sydney for allegedly making threats against New Year's Eve celebrations in an online blog, authorities said Friday.

The arrest came a week after police said they had foiled a "significant" Islamic State-inspired terror plot for Christmas Day targeting central Melbourne with explosives.

The 40-year-old man was to appear in court later in the day on charges of "making threats relating to New Year's Eve", a police statement said.

Police did not provide details about the threats.

Sydney is gearing up for the giant annual New Year's Eve fireworks party on the harbour with a crowd of more than one million expected.

Acting on a tip-off from the public, officers from the New South Wales Police Force Terrorism Investigation Squad arrested the man on Thursday at Sydney's international airport as he returned from London.

Documents and hard drives were seized after searches of a home and a storage facility in the city.

Police charged the man with possessing "documents containing threats... concerning online blogs".

He was refused bail prior to an appearance at Parramatta local Court.

"Investigations into this matter so far indicate this was an isolated incident," said Deputy Commissioner Catherine Burn.

"As a consequence, we are confident that there are no current or specific threats to New Years Eve... people should enjoy the celebrations."

At least a dozen terror attacks have been prevented in Australia in the past two years, according to officials.

But four have taken place, including the murder of a Sydney police employee last year.

Counter-terrorism police have made a large number of arrests since late 2014, with the youth and depth of radicalisation of many of those detained a growing concern.