Developers of the i360 tower will back the project with millions of pounds of their own money, according to official council papers.

Controversy has surrounded the project in recent weeks after the Green Party, later followed by some Conservatives, decided to back a £36 million Government loan to Brighton and Hove City Council, which will be handed straight to developers.

Councillors on the policy and resource committee will next week debate the plans for the project that has nearly doubled in cost to £46.2 million from when it was initially proposed in July 2012.

Coast to Capital LEP, a partnership between public authorities and a private company which promotes economic growth, will provide £4 million, but the revelation that developers Marks Barfield will provide the final £6 million to the project has increased confidence in the project.

According to the loan and equity distribution agreement, Marks Barfield will see a financial benefit from the plan only once the council’s major debt has been repaid and Coast to Capital has also been reimbursed.

If the final deal is agreed at the committee meeting on Thursday the council will receive £985,000 a year for 25 years – thought to be worth about £21.2 million in total – £60,000 in business rates and £70,000 in Section 106 payments, which will benefit the local community.

The council is expected to also get an extra £300,000 income from Regency Square car park, and council-owned seafront properties are expected to increase in price.

And in an added bonus the council would receive 50% of any extra cash created if the attraction does better than expected, to repay the loan early.

Geoffrey Theobald, leader of the Conservative Group in Brighton and Hove, whose members are split on the plans, said the latest financial revelations provided a good omen for the project’s future.

He said: “The fact that the developers have put a significant amount of their own money and time into the scheme over a considerable period makes me even more confident that the i360 is going to be a success.

“The top experts and advisers they have been using over this time would also involve substantial expenditure.

“Let’s not forget that this is the same team of developers that delivered the hugely successful London Eye.”

Green convenor Jason Kitcat said: “This is a unique opportunity to help create a world class landmark for our city, and we ask other councillors to join local businesses and residents in supporting the proposal.”

But Labour’s Warren Morgan remained steadfast in his party’s opposition to the project, an opinion shared by many in the Conservative Party including MP Simon Kirby, adding that he thought it was wrong for the council to commit taxpayers to nearly £40 million of debt.