Assistant Police Commissioner Michael Fuller said it was common for counter-terrorism officers to be involved in New Year's Eve celebrations but they were not always based at police headquarters.

"They will certainly be a big part of the operation," he said.

"It's important when you have the police operation centre stood up that you have all areas of the organisation there to ensure that we work seamlessly to provide a higher level of safety for the public."

The NSW Police counter-terrorism command was in discussions with its partner agencies "daily" in the lead up to New Year's Eve, Mr Fuller said. Counter-terrorism officers will join mounted police units, the public order and riot squad, the tactical operations unit and the police force air wing on the beat on Wednesday night.

All up, police will work more than 3000 additional shifts compared to a normal evening.

Mr Fuller said the heightened presence was usual on New Year's Eve and "it's got nothing to do with recent terror threats". The police presence increased every year in line with rising attendance, he said. More than 1.5 million revellers were expected to head to the harbour this year.

Sydney has been on high alert since the Martin Place siege on December 15 and Prime Minister Tony Abbott's pre-Christmas announcement that increased terrorism "chatter" made an attack "likely".

Mr Fuller confirmed on Saturday there was no intelligence on terrorism plots related to Sydney's New Year's Eve celebrations and planning for the event had not been altered by the siege.

"There is always chatter but there's no chatter that's specific to New Year's Eve," he said.

"Planning has gone ahead as it was the month before, and the month before that. Nothing has changed other than the way we brief police."

A new evacuation plan for the city had been in place since the national terror alert level was raised from medium to high in September, Mr Fuller said.

Large crowds at Carols in the Domain and the Boxing Day sales indicated people were undeterred by recent threats, he said.

"We know that Sydneysiders are confident to come out and we'd certainly like to see them out in big numbers for New Year's Eve," he said.