Melbourne airport rail delays as talks hit turbulence

A Melbourne airport rail link is unlikely to be completed on time because negotiations with the airport have been "frustrating", the deputy premier says.

The multimillion dollar project connecting the city to Tullamarine was originally due to be completed by 2029, with new stations and a sky rail bridge to be built.

But Deputy Premier Jacinta Allan said the government expected that completion date would be pushed back. 

"It has been challenging to negotiate with the airport about how the project will be delivered on the land that they lease from the federal government," she told ABC Radio Melbourne on Monday.

"Those negotiations, particularly with the airport, have at times been a little frustrating, they've been challenging and they have put real pressure on the completion date."

A Melbourne Airport spokesman said the timing of the project was a decision for government.

"The airport rail station needs to work for all people who come to the precinct, not just those who will come by train," he told AAP.

"Melbourne Airport is subject to planning requirements as set out in the federal Airports Act (1996) and is working through these with Rail Projects Victoria."

The Victorian and federal governments are each contributing $5 billion towards the project, which is expected to cost between $8b and $13b.

In 2018, Melbourne Airport was part of a consortium offering $5b towards the project with the aim of installing a tunnel.

But with rising state debt, there have been reports the Victorian government was looking to cap spending on the rail link.

Ms Allan said the government was in discussions with the Commonwealth about the project over the delayed negotiations with the airport. 

"Not the budget pressure or some of the budget back and forth, which is perfectly normal," Ms Allan said. 

"We've been talking to them about how the completion date is under pressure and what that means in the longer term."

Opposition Leader John Pesutto said the government should stop accusing others when its projects don't go to plan.

"They have been in office for nine years nearly," he told reporters.

"The Andrews government needs to take responsibility, not take the opportunity to blame everyone else that it can for mistakes it wholly owns."

The Victorian government is due to hand down its budget on May 23. The federal budget will be delivered on May 9.