Brussels  - A pair of robbers on Thursday made off with a nude painting by surrealist Rene Magritte valued at up to 4 million euros (5.9 million dollars) in broad daylight, police said.

The raid happened at a house in the Brussels suburb of Jette, where Magritte lived and worked from 1930 until 1954. It now serves as a museum.

Just after 10 am (0800 GMT), a young man approached the museum, which can normally only be visited by appointment, and convinced staff to let him in. He then pulled out a gun and demanded that they let his accomplice enter.

The armed man then ordered three museum workers and two tourists to lie down while he and his companion removed the 1948 painting, entitled "Olympia," from its frame.

The two men then made off in a car while museum staff raised the alarm.

Neither young man was wearing a mask or gloves, a police spokesman said. Federal forensic investigators have been called to the scene, and experts are preparing a photo-fit picture of the robbers.

The Belga news agency wrote that the painting was worth up to 4 million euros. Other reports value it at closer to 1 million euros. dpa