PRAGUE (Reuters) - The head of Britain's MI6 foreign spy service invited discontented Russians to share their secrets with British intelligence services.

"I invite them to do what others have already done this past 18 months and join hands with us," said Richard Moore, the chief of the Secret Intelligence Service during a rare public speech on Wednesday.

"Our door is always open. We will handle their offers of help with the discretion and professionalism for which my service is famed. Their secrets will always be safe with us."

(Reporting by Michael Holden, writing by Sarah Young, editing by William James)