Four Romanians behind an art robbery in the Netherlands have been ordered to pay over €18m, with the fate of the stolen masterpieces by Picasso, Monet and Gauguin still a mystery.

Seven masterpieces temporarily on display at the Kunsthal Museum in Rotterdam were stolen in 2012 in a raid that lasted only three minutes, in what the Dutch media called "the theft of the century".

A court in the Romanian capital ordered the robbery's mastermind Radu Dogaru, his mother Olga, Eugen Darie and Adrian Procop to reimburse the museum's insurance company. 

"We will contest the ruling," Catalin Dancu, the Dogarus' lawyer, told AFP. 

"In the first place, we don't believe the stolen paintings were the originals and secondly it is up to the museum to pay because it took the stupid risk of displaying the artwork without a proper surveillance system," he added.

Among the paintings estimated to be worth €18.1m were works by Picasso, Gauguin and Monet that belonged to the Triton Foundation.
None of them was equipped with an alarm.

The canvases were transported to Romania hidden in pillowcases and prosecutors think they were destroyed after a failed attempt to sell them.

Olga Dogaru told investigators she burned the paintings in her stove in the sleepy village of Carcaliu in eastern Romania, seeking to destroy evidence against her son.

She later retracted the statement, but a separate investigation is under way to determine if the masterpieces did end up in ashes.

Radu Dogaru, 30, who admitted planning the robbery, was sentenced to six years in jail in February, and his accomplice Darie to five years and four months in jail.

Procop was handed a jail sentence of four years and eight months while Dogaru's mother jailed for two years.