A Norwegian painting featuring 12,400 euros ($A20,600) worth of cash glued to a canvas proved too tempting to thieves, who made off with it at the weekend.

Some 100,000 bills of 1,000 kroner each were glued to Norwegian artist Jan Christensen's two-by-four-metre canvas, entitled Relative Value, the MGM Gallery in Oslo said.

The robbers broke into the gallery on Saturday night by smashing a window.

Then, proceeding methodically, they cut each bill off the canvas individually and left the cumbersome frame behind.

"Apparently they are nice because they took the canvas out of the frame," gallery owner Marina Gerner-Mathisen told AFP.

The thieves then left the building.

"When the security people arrived a couple of minutes later they were gone," she said.

She says a police investigation is under way.

- AFP