The Socialist Party and the Christian Democrats in Amsterdam are demanding that heads must roll after a damning report on the building of a new metro line slammed the city's executive for political ineptitude.

A public inquiry into the massive engineering project, which is now way over budget and years behind schedule, concluded that Amsterdam's political leaders should never have given the go-ahead for building to start.

The report says risks were ignored, insurance was insufficient, and effective organisation was lacking for years on end, saddling the city with a huge financial burden.

The committee behind the inquiry has refused to name names, focusing instead on the process itself, but the role played by Amsterdam's mayor Job Cohen is already under discussion. The Christian Democrats say he has been found "desperately wanting".

Labour, the largest party in Amsterdam, insists that there is no need to call the position of the city's executives into question. Parliament will hold an emergency debate on the issue on Thursday.