A £450,000 rise in the cost of delivering York’s community stadium scheme has been questioned by councillors who want it placed under fresh scrutiny.

City of York Council’s cabinet has approved a revised business case for the £19.2 million Monks Cross project, including a 6,000-seater stadium for York City FC and York City Knights alongside community facilities.

But although the scheme’s overall cost has remained the same, the project costs – relating to the search for an operator to run the stadium and York’s other public leisure facilities – have increased from £750,000 to £1.2 million between March and November. Meanwhile, the cost of the stadium itself has fallen by £350,000, to £10.65 million.

Councillors Ian Gillies, Mark Warters and Dave Taylor have now called in the cabinet’s decision on the business case, as well as its agreement to offer GLL – the current operators of Huntington Stadium, Waterworld and Courtney’s gym – reduced rent for a year until March 2014.

GLL told the council on October 1 that its losses meant it would terminate its lease in six months. The new agreement – financial details of which have been kept confidential – can be extended until June 2014, with the authority underwriting any losses in its final three months, but this was preferred to either closing the facilities or returning them to council control.

The call-in – which can lead to the cabinet being asked to revisit its original decisions – will be discussed at a scrutiny meeting today. Coun Gillies said the business case changes were “not particularly obvious and transparent”, particularly the increased project costs.

He raised concerns over potential “medium and high” risks associated with the project – mainly funding matters – becoming “unacceptable”, as well as over the GLL deal’s impact on the project’s “financial stability and sustainability”.

Construction work on the stadium is now unlikely to begin until June 2014 and be completed the following July, later than originally anticipated and meaning City and the Knights are likely to ground-share for two seasons.

A cabinet report by stadium project manager Tim Atkins said the revised business case was due to more “project management resources” being needed because an operator was being sought to run other leisure facilities as well as the stadium, which was not the case when the budget was originally set.

He said the additional costs would be “balanced out over the life of the project”, with fees increasing but more of the future risk potentially being passed to the operator, making it “a more cost-effective package”.