The book is part of the service's attempt to be more open and comes as Dame Stella Rimington hands over her post as Director-General of MI5 to Stephen Lander.
Among a review of MI5's work it says that although the threat of espionage from the former Soviet Union has greatly diminished, there has been a recent upsurge in spying by Russia and other countries.
The report says: "In the UK, after a period of initial retrenchment following the rise to power of President Yeltsin, both the Russian civilian and military intelligence services have renewed their efforts to post intelligence officers to London." It adds that the majority of spies are run by foreign handlers based in Britain.
Counter-espionage takes up about a quarter of MI5's efforts. The service employs about 2,000 people and has a budget of pounds 800m. Fighting international terrorism takes up about a third of its resources and Irish terrorism absorbs 39 per cent - down 5 per cent since last year. This trend is expected to be reversed since the breaking of the IRA ceasefire last month.
Under a Bill currently going through Parliament, MI5 will for the first time be allowed to investigate traditional serious crime, such as money laundering. Among some of its other current work is the investigation of attempts by foreign countries to obtain material and expertise for nuclear, chemical and biological weapons from Britain.Reuse content