Building more affordable homes on the first phase of a major regeneration scheme risks pushing the council’s debt up to worryingly high levels, opposition councillors have warned.

The Conservative Group says the council’s borrowing will triple on Meridian One – the first phase of the 10,000-home Meridian Water development – after it struck a deal to boost affordable housing on the scheme to 50 per cent.

Enfield Council will buy 230 homes to offer for affordable rent on the site – up from just 75 under a previous agreement with developer Galliford Try.

The remaining affordable housing will be offered at “intermediate rent”, with the overall number of homes on the site expected to increase to more than 900.

The Conservatives warn this means the cost to the council will climb to more than £50 million – adding to its substantial debt pile, which is already forecast to rise to more than £1 billion by 2020.

This debt creates interest that is repaid from the council’s revenue account – which also funds waste collections, social care and other services.

Cllr Edward Smith (Conservative), Cockfosters, said: “The cost of Meridian Water has gone up enormously compared to seven or eight years ago.

“The figure for the first phase is extraordinary. This would be a concern to any council, but it needs to be seen in context of the mountain of debt Enfield Council already has.

“When we accumulate debt, we have to pay it off. The interest is paid out of the revenue account, which also funds waste collection, social services and all the things that the council are concerned about.”

Conservative leader Cllr Joanne Laban said her group would have considered taking a different approach to Meridian One.

She said: “We back building more homes, especially on brownfield sites.

“Another way of getting the money is to do the first phase at 40 per cent affordable, get the income back and look to increase [affordable homes] on the next phase, so the income comes first.”

The Conservatives’ claim that the council is building too many affordable homes on Meridian One follows criticism from Labour councillor Cllr Tolga Aramaz that it is not providing enough affordable homes at social rents.

An Enfield Council spokesperson said: “The financial model approved for Meridian Water has been based on industry norms and signed off by independent and well-respected accountants.

“While the primary aim of Meridian Water is to benefit the local community – including a significant provision of affordable housing – the overall scheme will be self-funding.

“Enfield Council’s priority since taking back control of the delivery of Meridian Water has been to ensure it benefits local people and helps to tackle the ‘housing crisis’ in the borough.

“While always ensuring that Council finances are safeguarded, we make no apologies for putting local people before profit.

“Enfield Council’s overall borrowing is robustly planned, managed and serviced – and independently audited.”