By Helen Fawkes
BBC correspondent in Kiev
The drawings collection is considered one of the most important in the world
More than 100 drawings stolen by the former Soviet Union during World War II have been officially given back to the Netherlands.
The Old Master drawings had been stored in a museum basement in the Ukrainian capital, Kiev, for more 50 years.
They were first looted from Holland by the Nazis, who it is thought had earmarked the pictures for Adolf Hitler's private collection.
But then, in 1947, they were stolen by the Red Army and taken to the USSR.
The art treasures were presented to Dutch Prime Minister Jan Peter Balkenende by Ukrainian President Leonid Kuchma at a ceremony in Kiev's Mariinsky Palace.
"Now we can see with our own eyes these wonderful drawings which we believed to be lost. They are more beautiful than we expected," Mr Balkenende said.
The 139 pictures are from the Koenigs Collection, which is considered to be one of most important collections of drawings in the world.
They were traced to Kiev by the Netherlands last year.
The drawings, which date mainly from the 15th and 16th centuries, were discovered still in their original black boxes with red seals at the Khanenky Museum in Kiev.
The recovered pictures are all by German masters and include a group of six apostles drawn by Hans Holbein the Younger.
When Mr Balkenende asked for them to be returned, the Ukrainian president agreed straight away.
"I think that Ukrainians derived no satisfaction from the fact that the drawings were kept in a museum basement," President Kuchma said.
Kuchma insisted the handover should not be seen as a political act
"Also, according to the laws signed after World War II, such things have to be given back to their original countries."
The Ukrainian leader insisted the handover should not be seen as a political act but the Dutch prime minister admitted that this occasion was bound to improve bilateral relations.
Despite the importance of the drawings, they were never put on show by the Soviet authorities.
But now they will be exhibited in Ukraine before being displayed at the Museum Boijmans Van Beuningen in Rotterdam in July.
"These precious things, which we thought we would never see, are now going back to Holland," said the Dutch prime minister.
"The Koenigs Collection is very valuable for Dutch people and it means more to us than the tens of millions of euros its worth."
But the Koenigs Collection will still not be complete.
More than 300 drawings from the same collection were traced to Moscow 10 years ago, but Russia has so far refused to hand them back.
Decades after the end of World War II, the problem of art ownership remains a difficult issue in the former Soviet Union.