U2 record tribute for Nelson Mandela's 93rd birthday

U2 have recorded a tribute in honour of former South African President Nelson Mandela's 93rd birthday

The Irish rock band taped a special performance of 'Happy Birthday' in Mandela's honour during a gig at Philadelphia's Lincoln Financial Field.

All four members of U2 gathered in front of Bono's microphone during their final encore and led the sold-out audience in wishing the human rights campaigner birthday greetings.

Bono has worked on behalf of Mandela's 46664 AIDS charity in the past, even co-writing the organisation's theme song with the late Clash singer Joe Strummer.

U2's version of 'Happy Birthday' will be shown to Mandela during a birthday party which is to be held at New York City's Four Seasons on Monday, reports the New York Post's Page Six.

Morgan Freeman, who portrayed Mandela in Invictus, will host the birthday celebration and NBC anchor Brian Williams, Star Jones and chatshow host Charlie Rose are among the invited guests.

U2 recently invited a blind guitarist on stage during a concert in Nashville to perform a tribute to the man's wife.

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Watch amateur footage of U2's tribute to Nelson Mandela below: