Rome

A trio of masked and armed robbers have made off with three of the most important works from the National Gallery of Modern Art in Rome after locking guards in a lavatory.

Italian art expert Achille Bonito Oliva estimated the combined value of the paintings - two by Vincent Van Gogh and another by Paul Cezanne - could be #21m.

The Cezanne, Le Cabanon de Jourdan, an unfinished painting, dates from 1906, the year he died.

The Van Goghs - The Gardener and L'Arlesienne - are also late works. Van Gogh painted L'Arlesienne, in early 1890, the year of his suicide; The Gardener was painted a year before, while he was at an asylum in St Remy, France.

Museum curator Sandra Pinto said the paintings would be almost impossible to sell because of their fame. She said the thieves might be acting on commission from a private collector or perhaps they planned to make a ransom demand.

Italian news agencies later reported that police were investigating a telephone call in which a man claimed to have the paintings.

''We will let you know the conditions, political as well, to have the Van Goghs and the Cezanne back,'' a male caller was quoted as telling the Adn Kronos news agency.

The museum's closed-circuit surveillance system had broken down a few days earlier and was not working during the robbery.

Security was largely in the hands of three unarmed guards, and what officials at a news conference described as an alarm system with several ''dead zones'' that was not connected to any police station.

The guards said they were forced at gunpoint to disable the alarm system, and herded into the lavatory an hour after the museum closed on Tuesday night.

Officials think the robbers entered the museum as visitors, then hid inside until it closed.

About two hours later, people at a cafe next door were locking up and gave the guards a call to see if they wanted coffee. When they got no answer, they went to the museum and saw a door ajar. After a call to a police emergency phone line went unanswered, they flagged down a passing police car.-AP