DUPLICATION of the North Coast Rail to the Sunshine Coast must not be sidetracked by any business case commissioned for a new fast transport network linking the region to Brisbane, the Gold Coast and Toowoomba, Opposition leader Deb Frecklington has declared.

Brisbane Mayor Graham Quirk and Deputy Premier Jackie Trad announced a push for a South East Queensland City Deal to create a 45-minute region linked by fast rail.

Ms Frecklington said the LNP supported the push for Very Fast Rail as long as projects like the North Coast Rail duplication don't go by the wayside while a business case was developed.

She said it was time commuters could get off the Bruce Highway and into trains for their daily journey to the city.

And Ms Frecklington said she would need to see the business case before committing to any Very Fast Train project.

She called on Premier Annastacia Palaszczuk to stop the blame game and get trains back on track following the loss of 470 a week in south east Queensland.

Fisher MP Andew Wallace (LNP) this week said while he would back any deal with benefits beyond the Brisbane municipality but said existing priority infrastructure projects with money on the table demanded state funding.

The South East Queensland City Deal would seek to lock in a rolling funding agreement involving all levels of government to deliver a funding pipeline over 15-20 years unaffected by election outcomes.

It comes after the federal government committed $390 million to North Coast Rail duplication and Labor's state budget commitment that fell short of matching it by $230 million.