The [FIDE] Congress unanimously decided to state as a general principle that a tournament in which one or more players for political reasons are prevented from taking part cannot be recognized as a FIDE tournament. Prior to the Berg en Dal tournament such an event had never occurred in the history of FIDE. (FIDE Review 1961)
The Berg en Dal tournament was played in the fifth FIDE World Championship cycle (C05). To put this in perspective, the current cycle, culminating next year in the Anand - Gelfand title match, is C24, and the next World Cup, 2011 Khanty-Mansiysk, is C25. The situation where 'one or more players for political reasons are prevented from taking part' has been a recurring problem in recent years, where the 2004 FIDE Knockout Matches in Tripoli, Libya, provided numerous examples. I recently wrote about this in The Worst World Championship Ever. Maybe it's due to the passage of time, but the early FIDE officers seem to have been wiser than the bumbling bozos currently in charge.
Incidentally, the 'Berg en Dal tournament' would be better called the 'Ubbergen tournament'. As mentioned in another clipping, Berg en Dal was a hotel in the town of Ubbergen, Netherlands.