Buy to let investors in the Norwich area could be ordered to find better ways of heating their properties or face prosecution. The warning was made by the City Council after it was discovered many flats in a residential housing block were too cold for human habitation.

Although the flats are privately owned, the Council is using new powers to inspect all 84 of the homes at the property in Earlham House, Earlham Road, Norwich, after tests found some of them to be rated as a category one hazard - likely to create a serious risk to health.

The lack of adequate heating was uncovered after the council used a Standard Assessment Procedure (SAP). Homes are rated for their energy efficiency from zero (very inefficient) to 100 (highly efficient).

The national average is 52, but in the samples carried out in ratings were only 11 in a larger flat and 25 in one of the smaller ones.

Tenants in all the flats are now being sent letters from the council saying that officers will be visiting their premises during the next few months to study the problem with the aim of bringing each flat up to a reasonable standard of heating and warmth.

The individual landlords would be expected to make any recommended improvements which may involve installing new heaters or better insulation.

If they refuse to do the work, the council could prosecute them or do the work itself and then demand payment from the landlord.

Speaking to the Norwich Evening News, Paul Swanborough, the council's private sector housing manager, said: “It is a 1960s block and has very poor heating and insulation, which means it is excessively cold and there were issues with fire precautions.

“We have been dealing with the fire precautions in association with Norfolk Fire and Rescue Service and brought about a lot of improvements, but we are now tackling the poor insulation and inefficient heating.”