The restriction follows research carried out by accountancy company PWC into Prorail's integrity. PWC discovered that four 3.5-year track maintenance contracts had been extended to 10 years in violation of tendering legislation. Prorail had also failed to inform the Ministry of Infrastructure of the contract extensions.

Prorail and the track maintenance contractors have mutually agreed to dissolve the contract extensions. The CEO of Prorail, Mr Pier Eringa, is now solely responsible for tendering these contracts.

The secretary of state for infrastructure, Mrs Wilma Mansveld, considers the irregularity an isolated incident, and not worthy of further investigation. However, she has instructed ministry officials to be more vigilant to detect such irregularities and Prorail to be more active in supplying information to the ministry.