The origins of paintings can usually be ascertained by the markings on its back. However, these markings have not been systematically documented on any database.

This means that investigators have to examine each work of art separately to determine its history.

So far, investigators have uncovered two paintings in Finland that were stolen by the Nazis.

Recently, state museums have begun to demand compensation from the investigators. They say that the extra work involved costs up to 30,000 euros.

The investigators themselves have been surprised by the demands for money. They say they have examined works of art at 27 museums and have never before been asked to pay compensation.

For the time being, the search for Nazi art has been suspended because of the squabble over money. The search has been financed by a private trust.

In most other countries, the hunt has been financed by the state.