Ex-RAF, navy and army pilots will be prosecuted for sharing military tactics with foreign powers under new laws.
The move comes as concerns arose over Beijing spying in Westminster and revelations that UK fighter pilots have been training troops in China.
It was revealed last year that 30 former British military pilots had been teaching the People’s Liberation Army, attracted by salaries of around £240,000.
Former UK Armed Forces personnel who trains foreign militaries around the world can now be prosecuted under the National Security Act.
Defence Secretary Grant Shapps said: “Anyone found to be acting against the UK’s interests by training our competitors’ militaries can now expect to be pursued and brought to justice.
“The government has acted decisively following the identification of this threat, and has made rapid changes to legislation to help shut it down.”
The UK government is also working with our allies experiencing similar problems to fight the issue internationally.
Security Minister Tom Tugendhat added: “In recent years we’ve seen attempts to harm our people, damage our economy and undermine our democracy.
“We’ve also seen attempts from countries such as China to solicit national secrets from former Armed Forces personnel.”