Sydney’s Town Hall busy train station was evacuated on Wednesday morning amid reports of a suspicious package.

NSW Police said later the threat was a hoax, although it caused major delays across Sydney’s rail network.

The nearby St Andrew’s Cathedral School was also put into into lockdown as police swept the station.

“SACS is in partial lockdown due to a suspicious package found at Town Hall station,” the school said in a text message to parents.

“We will advise when given police clearance.”

City commuters were advised to catch buses instead.

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NSW Police confirmed at 11.40am that a police operation was underway at the rail station after an earlier emergency call.

Officers searched the station and surrounds, but about 12:30pm confirmed nothing had been found, allowing trains to resume.

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Commuters caught up in the saga were urged to delay their travel, with major flow on delays still plaguing the train network hours later.

Buses were still supplementing trains in some areas later on Wednesday.

-with AAP