Singers Simon & Garfunkel have canceled an upcoming North American tour because Art Garfunkel has a condition affecting his vocal cords.
The "Old Friends" tour, reuniting the legendary but fractious 1960s partnership that produced hits like "Bridge Over Troubled Water" and "The Sound of Silence", had already been rescheduled once this year, from April to July.
But a statement posted this week on their official website, said the pair was now postponing indefinitely the dates in Canada and the U.S.
"According to his doctors, Art is expected to make a full recovery, however they cannot predict an exact timeline," the statement said.
"This condition (paresis) inhibits the duo from performing shows at the highest possible level and it is for that reason and out of respect for their fans that Paul and Art have decided to put the tour on hold," the statement added.
Vocal paresis is a weakness of voice box muscles affecting pitch and the ability to transition smoothly to higher notes.
Garfunkel, 68, said; "I do feel bad about disrupting so many people's plans but, as I continue to mend, I can't yet bring my 'A Game' to a tour."
Simon & Garfunkel toured Australia together last year and performed at the Rock And Roll Hall of Fame 25th anniversary concert in New York in October.
But the last time they toured North America together was on the 2003 "Old Friends" tour.
The pair split up in 1970 because of artistic and personal differences, reunited for a handful of appearances in the 1980s and 1990s and performed together for the first time in a decade at the 2003 Grammy Awards, before embarking on their 2003-2004 reunion tour of the United States and Europe.