Here is more from the BBC:
Fraser Cameron, who runs the EU-Asia Centre think tank, is suspected of passing sensitive information about the EU to two spies allegedly posing as Brussels-based journalists.
He is alleged to have exchanged the information for thousands of Euros.
But Mr Cameron told The Times the allegations were "ridiculous".
The businessman, who worked for Britain's Secret Intelligence Service from 1976 to 1991, says he has no access to any "secret or confidential information".
Numerous people who work at think tanks around the world have been accused of giving information to foreign spies.
Here is a link to the EU-Asia Centre, which was established in 2011.