The warning comes from Waveney District Council (WDC), which is reminding landlords letting properties of three or more floors to at least five unrelated people who share some facilities like kitchens or bathrooms, that they must be licensed with the council.

Due to the Housing Act 2004, owners of such properties must have a Houses in Multiple Occupation (HMO) licence. The law does not apply to buildings converted into self-contained flats with no shared amenities.

A council spokesman said he was aware that many landlords had not applied for licences.

He said:

"We would like to encourage landlords and managers of relevant HMO properties to make contact with WDC so we can work together in making an application and ensuring the property meets current standards.

"We are also targeting properties in areas where we think there are unlicensed HMOs and enforcement action will be taken."