The metro line to Hook of Holland will not be ready until May at the earliest because of further delays caused by computer problems.

RTV Rijnmond reported on Tuesday that the deadline to install and test safety software for the RET trains at the end of last year had been missed. The delay raises fears among local businesses that the line will not be ready in time for the summer holiday season.

The upgraded line from Schiedam was originally due to be completed in September 2017, but has been hit by a series of delays and spiralling costs. Last February Rotterdam alderman Pex Langenberg resigned after it emerged the project had overshot its budget by €90 million.

Rotterdam city council has set aside an extra €6.5 million for compensation and replacement transport services, but the money will run out at the end of July. A spokesman said: ‘We are aware that this will mean further disruption caused by longer travel times.’