Over 25% of cleaning firms are breaking the law, according to an investigation by the social affairs and employment inspection agency SZW.

Inspectors visited 1,450 cleaning firms last year, together with representatives of the tax authority, local councils and benefit agency UWV, and found that 27% are not keeping to the rules.

Most of the offences occurred in small firms with under 50 workers, which are mainly active in the fast-food sector, transport, construction, hotels and window cleaning for private homes, the NRC reports.

Fraud

Offences included benefit and tax fraud, incomplete bookkeeping, low pay and exploitation.

The inspectors also discovered 324 illegal workers: 41% from Bulgaria and 21% from Romania.

In total, €37m was recovered or charged in fines.

Large cleaning companies affiliated to the sector organisation are much less likely to break the law, the NRC reports.

Last year saw a series of strikes by cleaning workers organised by the trade unions because of the poor pay and conditions.