The secret project which Norwich City Council was prepared to lend millions of pounds to involved Norwich International Airport, it can be revealed.

As reported, the city council agreed to make £9.7m available for a 'strategic asset investment' at a behind-closed-doors meeting more than a year ago.

The loan was not given, but the council was prepared to borrow or use money from its cash flow in order to make it. It has refused to reveal what the mystery project was.

The council said it was - and still is - commercially sensitive. But the authority's own papers have unintentionally revealed the loan was earmarked for Norwich International Airport.

That detail was revealed in papers which went before the council's scrutiny committee last month. An annexe to the budget papers stated that the council's projected income for the next 12 months would be £222,000 less than anticipated, because of the removal of interest which would have been generated through an 'airport loan'.

When that same report was presented to full council last week, the word airport had been replaced with 'commercial' loan.

Concern over the mystery millions and the way the decision was taken in private was raised by Green councillors at a council meeting last week.

In response, Labour said the details were commercially sensitive, so statute meant the decision had to be taken with the public and press excluded.

The city council says it remains commercially sensitive, but stressed it would always ensure a good return on any investment. Norwich International Airport did not return calls.

Norwich City Council and Norfolk County Council used to be majority owners of the airport. But they sold most of their stake in 2004.

The airport was bought last summer by Regional and City Airports, part of the Rigby Group of companies, with the two councils retaining a minority interest.

In 2013, the airport secured planning permission for the first step of a planned Norwich Aeropark. That was for Air Livery consolidate its UK business in Norwich, with five 17-metre tall units to be built and 150 jobs created.

And the airport's plans for a £12.5m aviation academy were handed a boost last month after a government growth deal secured £3m towards the project.

That project will support 80 engineering apprenticeships per year, as well as degree-level and further and higher education courses in engineering, airport operations and cabin-crew training, for hundreds of students.

The remainder of the investment is expected to come from loan funding and the private sector, who will provide the 'real world' training experience with a full size aircraft, plus additional equipment and aviation facilities.

• What do you think? Leave your comments below.