The royal yacht cost the Dutch state €1.5m in maintenance over 11 years, according to the Volkskrant.

Princess Beatrix – queen of the Netherlands until she abdicated in 2013 – was given De Groene Draeck yacht by the Dutch people for her 18^th birthday in 1957.

But there have been increasing concerns about the annual bill for the 15-metre boat, which has reportedly been twice as much as budgeted for since 2012.

Last autumn prime minister Mark Rutte told MPs that the ship would require €95,000 a year in upkeep in the next five years, but experts at the time said it could be done for just €30,000. Rutte announced that he would get a quote from an independent specialist.

Now the Volkskrant says the yacht cost €1.5m to maintain from 2004 to 2015, money that comes out of the public purse. Each year the vessel is overhauled at the naval shipyard in Den Helder which the Dutch paper claims ‘treats the job as a military operation, from the project plans drawn up each year.’

‘In short,’ says the Volkskrant, ‘De Groene Draeck is maintained like a warship, while it is actually a rarely-used pleasure boat.’

Although Beatrix is known to pay towards the costs, the maintenance of the boat is classified a secret. The Volkskrant says its figures come from the defence and general affairs (‘algemene zaken’) ministeries, under freedom of information requests.