The laws on official secrets typically (and uncontroversially IMO) forbid any unauthorized handling or distribution of classified material. This is not a US-pandering post-9-11 knee-jerk thing, it goes back at least to WWII, and probably much longer.
Interestingly, the US has no corresponding law. There were previously some similar terms in the Espionage Act, but the courts have held them to be unconstitutional. A civilian who comes in to possession of state secrets is not obligated to keep them secret. Selling them to foreign governments would probably still constitute espionage, but selling them to newspapers is protected under free speech/free press.
The situation is not so clear with respect to information classified as Restricted Data or Formerly Restricted Data under the Atomic Energy Act. See US vs. The Progressive.
True, that issue was never actually decided. The courts don't usually take an interest-balancing approach with respect to freedom of speech though. It seems unlikely that kind of restriction would be upheld.
Interestingly, the US has no corresponding law. There were previously some similar terms in the Espionage Act, but the courts have held them to be unconstitutional. A civilian who comes in to possession of state secrets is not obligated to keep them secret. Selling them to foreign governments would probably still constitute espionage, but selling them to newspapers is protected under free speech/free press.