The giant investment fund offering $7 billion to build Melbourne's airport rail link is urging state and federal support for a project that would create thousands of jobs amid warnings COVID-19 has impacted the project's timeline.

Prime Minister Scott Morrison and Premier Daniel Andrews were close to securing a deal on the $8 billion-$13 billion project before the coronavirus crisis hit and were poised to make an announcement.

Prime Minister Scott Morrison and Premier Daniel Andrews speaking to media about the airport rail link at Sunshine train station in April, 2019. CREDIT:STEFAN POSTLES

Federal Cities and Urban Infrastructure minister Alan Tudge confirmed on Friday the project's timeline had been pushed out slightly due to COVID-19, with the urgent task of curbing the spread of the virus occupying both levels of government in recent months.

However, The Age understands that a decision on the rail line through Melbourne's north-west is now set to be made in coming weeks.

IFM Investors, which leads the AirRail consortium including Melbourne Airport, Southern Cross Station and Metro Trains, has called on the state and federal governments to consider its proposal to build a seven-kilometre tunnel between the city and Sunshine, arguing it would "super-charge" the Victorian economy in the face of a devastating pandemic.

If built, the tunnel option would "generate 13,000 jobs, super-charge the local economies of the western suburbs and regional Victoria, and boost the tourism sector as the state emerges from the COVID-19 pandemic" executive director of global asset management Danny Elia said.

"IFM Investors' Melbourne AirRail proposal will be a strong investment for millions of Australians. It will enhance Melbourne's standing as a world-leading place to live and visit. Industry super funds stand ready to work with state and federal government to get going as soon as we can.”