Concern about the growing media presence of British spies has been raised by MPs on the parliamentary Intelligence and Security Committee.
A report by the ISC refers to newspaper interviews by MI5 and GCHQ bosses, and the head of MI6's Twitter account.
Spy chiefs have also appeared on the BBC, and the head of GCHQ is set to guest edit Radio 4's Today programme.
Agencies have used social media and interviews to explain their work and increase recruitment and diversity.
In its annual report, the committee said it recognised the "important role public outreach can play in attracting employees by opening up about the culture and working practices in such secret organisations" - but it said such activity "must be undertaken in a strategic and considered manner".
It added: "The committee is concerned that, if media engagement strategies go too far, they risk trivialising the important work of the agencies and diverting their focus from national security priorities. Social media is also known to be a battleground for covert hostile state action, so any enhanced media engagement should not undermine the agencies' ability to act covertly and keep the UK safe."
It pointed to a number of recent interviews by spy chiefs - and the head of MI6's Twitter account.
Richard Moore, also known as 'C', tweets far more than any other head past or present of an agency.
The MPs also pointed to anonymised media interviews with lower-ranking employees, saying there had been "a clear step-change for the agencies, who have traditionally shied away from such exposure - particularly of junior staff".