The naming of the successful tender is the worst-kept secret in the industry,coming just after Labor piled pressure on Mr Constance during question time in Parliament to confirm that Transit Systems had indeed won the contract.

The company already has contracts with the state government to operate other routes in Sydney's west such as those at Parramatta,Fairfield and Liverpool.

About 1200 bus drivers are affected by the latest decision to privatise services. In all,STA has about 3700 drivers in Sydney and 12 bus depots.

The Rail Tram and Bus Union accused the Transport Minister of ignoring tens of thousands of commuters who did not want the bus services privatised,as well as a written guarantee to drivers in late 2016 that there jobs were safe.

"He’s ignored them. I completely understand why the community is furious,” Mr Preston said.

“We call on Minister Constance to guarantee Sydney commuters that stops will not be closed and bus services not be cancelled under a private operator.”

The government said bus drivers affected by the awarding of the contract to Transit Systems would be offered jobs with the private operator and an 18-month employment guarantee.

In May last year,about 1200 Sydney bus drivers walked off the job for 24 hours in protest against the plan to privatise the bus services in the inner west.

The union and the government have also been in a battle on another front for weeks over a new pay deal for thousands of Sydney rail workers.