Doors with gilded handles leading to an Art Nouveau lounge, Louis XV-style furniture and a 148-year-old locomotive: remnants of some of the world's oldest royal trains are on display in the Dutch city of Utrecht.

From Britain, Ireland, Sweden, Denmark, Belgium, the Czech Republic and Portugal - the trains were brought together for the first-ever exhibition of its kind, opening to the public in the Dutch Railway Museum on Thursday.

Entitled: "Royal Class, regal journeys", the exhibition was officially opened on Wednesday by the Dutch monarch, Queen Beatrix, who arrived for the occasion in her own private train from The Hague.

Hosted in a colonial-era station, the exhibition starts with the Dutch royal family's 19th century waiting room at The Hague Central Station, restored in Utrecht with all its wood panelling and a fireplace decorated with tiles made from the Netherlands' famous blue-and-white glazed Delft pottery.

A green train constructed in 1862 for the Portuguese queen Maria Pia is the only specimen on show in its entirety.

A gift from her father, Italian king Victor Emmanuel II, the 33-metre-long (36-yard) train comprises the steam locomotive and its tender (a compartment that held the coal and water), the queen's carriage and another wagon.

The queen's coach - lavishly upholstered in gold and red velvet and cream-coloured silk brocade, has a sleeping compartment with a porcelain toilet and a separate compartment for her attendants.

The smallest wagon in the exhibit, all of 6.4 metres long, is also "the oldest preserved royal wagon in the world," museum curator Jos Zijlstra told AFP.

Constructed in 1842 for the excursions of the English queen Adelaide, it resembles an old-fashioned stage coach and included an innovative feature: a foldaway bed.

The saloon coach built in 1910 for Austrian archduke Franz Ferdinand has more modern trimmings: electric lighting and steam warming, a separate toilet compartment and a bedroom with two beds.

It was on board this wagon that the heir to the Austro-Hungarian throne travelled to Sarajevo in June 1914, where he was assassinated in an act that sparked World War I.

In contrast to much of the pomp and splendour, the two blue wagons of the former Dutch queen Juliana, mother of the incumbent, are more sober: the 1950s style bathroom and kitchen reminiscent of an average middle-class house of the era.

Getting the wagons to The Hague required "massive logistics", said Zijlstra.

"Some came via railroad," he said - including the lounge and restaurant wagon of Belgian king Albert, dating from 1912.

In the king's dining room cart, furnished in the style of Louis XV complete with cream-coloured wood panelling, a dining table is set for ten people with silverware, plates and wine glasses.

The lounge, with two armchairs and a white couch, is in the Art Nouveau style.

Some of the wagons "were so fragile that they were hoisted onto removal trucks with huge cranes", or had to be transported by ship, said Zijlstra.

Bringing the trains to the Netherlands and the renovation work cost "about 550,000 euros (750,000 dollars)," added the museum's financial director Marina de Kanter.

The exhibition is open to the public until September 5.