Los Angeles, June 6 (Reuters): The award-winning British playwright Peter Shaffer, best known for penning Amadeus and Equus, died today in County Cork, Ireland, of pneumonia and age-related issues, his long-time agent said. He was 90.

Shaffer was surrounded by friends and family at the time of his death, just a few weeks after his 90th birthday, agent Dennis Aspland said.

Born in Liverpool, and educated in London and Cambridge, Shaffer established his career with 1954's The Salt Land, produced for BBC television, and comedies such as The Private Ear and The Public Eye, both starring Maggie Smith.

His drama Equus won numerous awards in 1975, including the Tony Award for best play, as did his drama Amadeus in 1981.

Shaffer was nominated for an Oscar in 1978 for his Equus screenplay and later won an Oscar for his screenplay adaptation of Amadeus in 1985.

Equus was revived most recently in 2007 on London's West End and New York's Broadway. Amadeus will be revived at London's National Theatre, which Shaffer was closely involved with, this autumn.

The playwright was awarded the Commander of the Order of the British Empire (CBE) in 1987 and was knighted in 2001 by Queen Elizabeth II. He is survived by his brother, Brian Shaffer.