SYDNEY, Australia (AP) _ Former British intelligence officer Peter Wright, whose best-selling autobiography ``Spycatcher'' accused security services of plotting to topple a former British government, died today. He was 78.

Wright died at his home in Tasmania of pneumonia, said a spokesman for lawyer Malcolm Turnbull. Turnbull represented Wright in a lengthy court battle when the British government tried to ban publication of ``Spycatcher'' in Australia.

Wright retired from Britain's MI5 counterintelligence agency in 1976 after 20 years' service and retired to Australia, where he wrote his memoirs.

His book accused British security services of trying to topple Harold Wilson's 1974-76 Labor Party government, eavesdropping on foreign embassies, bungling cases, stealing documents and plotting to assassinate Egyptian President Gamal Abdel Nasser.

Wright also accused the late MI5 director Sir Roger Hollis of being a Soviet agent, a claim the government said was never substantiated.

The book was banned in Britain, and the government waged a lengthy, costly and ultimately unsuccessful battle to prevent its publication in Australia. It became an international best seller.

Former Prime Minister Margaret Thatcher said if Wright ever went back to England he would be prosecuted for breaching the country's Official Secrets Act.

``He lived in exile but he gets the last laugh,'' said Wright family spokesman Peter Murray. ``He's returning in death.''

Wright is to be cremated and his ashes scattered over the waters of the Blackwater Sailing Club in southern England, said family spokesman Peter Murray.

After retiring from MI5, where his job was to track down traitors, Wright had lived in Cygnet, a small town south of Hobart where he operated an Arabian horse breeding ranch.

Wright is survived by his wife, Tessa, two daughters and a son.