President Francois Hollande's government is setting up a group of experts to actively find families, rather than waiting for claimants to make the first move.

The new drive starts next month and follows a French Senate report last month that called on the government to stop dragging its feet in rooting out owners.

It suggested making the archives on looted art at the foreign ministry and the Louvre museum more accessible, including the scanning of thousands of relevant documents languishing in cartons.

"It may be one of our last chances to find the owners," said Jean-Pierre Bady, part of the French Commission for the Compensation of Spoliation Victims. "Seventy years is a long time, but it's never too late to make things right," he said.

The Nazis seized hundreds of thousands of works of art from Jewish private collections between 1933 and 1945 in what amounted to the biggest mass art heist in history. Many of the works were returned to governments by the Allies in 1949 but most unclaimed art sunsequently ending up in museums.

France set up the so-called Matteoli Mission in 1997, which created the Commission for the Compensation of Spoliation Victims to address the conssequences of Nazi crimes.

The Commission has returned one artwork per year on average and handed out 33 million euros in compensation for lost pieces based on the estimated value of the paintings during the war.

The first sign the process is set to accelerate has been the culture ministry's move to return seven paintings looted by the Nazis to two Jewish families. Three are held by the Louvre.

The works by Alessandro Longhi, Gaspare Diziani and Pieter Jansz van Aschwere, among others, were earmarked to go on display in the Fuhrermuseum - a private museum Adolf Hitler had planned to stock with looted art from around Europe. The two families had been demanding their restitution for several years.

The seven paintings were on a list of 163 works considered to be "with certainty or with strong belief" among Nazi-looted art objects. These will be the priority of Mr Hollande's new group in tracking down descendants of victims.

It is thought that most of the major works awaiting claims belong to families from Central and Eastern Europe, particularly Poland, the former Czechoslovakia, Austria and Hungary.