The duo were one of the 1960s' most successful acts

The former duo, who have a history of strained relations, have been said to be considering playing at the Grammy Awards ceremony in the US on Sunday.

The pair sang together in private on Wednesday, uniting for the first time since 1993, a spokesman for Simon said.

They are due to receive a lifetime achievement award from the National Academy of Recording Arts and Sciences, which hosts the Grammys.

Simon and Garfunkel split up 33 years ago to pursue solo careers after becoming one of the most successful pop acts of the 1960s.

Simon's spokesman said: "They got together (on Wednesday) and had a wonderful time.

"They got together as two great old friends and sang for the first time since 1993. They're thinking of performing at the Grammys, but they're not sure if they have enough time."

Garfunkel (pictured) and Simon have had a strained relationship

Simon and Garfunkel were reportedly due to meet Grammys writer-producer Ken Ehrlich at the ceremony's venue, Madison Square Garden in New York City.

They will receive their accolade at a pre-awards ceremony in their home town on Saturday.

Simon and Garfunkel met as children in the New York borough of Queens and released their first record in the 1950s under the name of Tom and Jerry.

During the 1960s they had worldwide success with hits such as Sounds of Silence, The Boxer and Scarborough Fair.

Over the years rock commentators have suggested that the duo endured creative tensions, caused in part by Garfunkel being in the shadow of Simon's songwriting talents.

Following their split they reunited for a few shows, including a 1981 concert in New York's Central Park watched by half a million people.