Avril, Paul Sing for Iraq's Children
The album also contains a contribution from Cat Stevens, marking his first pop song in more than a quarter of a century. Lavigne sings her own take on the Bob Dylan classic, "Knocking on Heaven's Door."
All profits from the 18-track album -- called, simply, "Hope" -- will go to War Child, the relief and development charity set up after the war in former Yugoslavia.
The charity, in a statement, stressed that "Hope" is not a political album.
"The plight of children transcends politics. These songs are a plea for hope without which the children of Iraq have nothing at all," said War Child.
McCartney, 60, who made a live recording of his song "Calico Skies," told Reuters: "Whatever the politics, whatever the rights and wrongs of war, children are always the innocent victims. So I am delighted to make this small contribution."
But speaking to the BBC in an interview Monday, the former Beatle went on to say that he believes it is too early to determine whether British Prime Minister Tony Blair and U.S. President George W. Bush's war on Iraq was the correct thing to do.
The musician conceded that only "time will tell."