Becker and Fagen have performed as Steely Dan since the 1970s

In a light-hearted letter to Wilson's brother Luke posted on their website, Walter Becker and Donald Fagen said the alleged "rip-off" was "uncool".

"Your brother has gotten himself mixed up with some pretty bad Hollywood schlockmeisters," they continued.

UIP, the film's UK distributor, has yet to make a comment.

In You, Me and Dupree, Owen Wilson plays an amiable slacker who comes to stay with his best friend and his new wife and proves impossible to evict.

'Major karma'

Becker and Fagan claim the character, named Randolph Dupree, was inspired by their Cousin Dupree, a travelling musician who "comes back home to plan [his] next move from the comfort of [his] Aunt Faye's couch".

"When it came time to change the character's name so people wouldn't know what a rip the whole thing was, they didn't even bother to think up a new name for the guy."

Luke and Owen Wilson both have films showing in US cinemas

Wilson, they claim, is "generating some major harsh-ass karma for himself" for leaving the band "totally out in the cold".

In their letter, the musicians invited the Wedding Crashers star to attend a concert they held in California last week and "apologise to our fans for this travesty", but the invitation was not taken up.

Steely Dan, whose 1970s hits include Reelin' In The Years and Rikki Don't Lose That Number, are touring the US with American singer Michael McDonald.

Cousin Dupree, taken from their 2000 album Two Against Nature, won a Grammy award for best pop performance by duo or group with vocal.