TMZ has the details:

The Red Hot Chili Peppers have postponed their upcoming U.S. tour .. over a CRUSHED BONE in Anthony Kiedis's right foot ... the band has announced.

The band released a statement saying, "Anthony recently underwent surgery to remove a crushed sesamoid bone and correct a detached flexor tendon in his foot."

For all you junior medical doctors out there -- the sesamoid bone is connected to Anthony's big toe.

Anthony is expected to make a full recovery -- and the band has posted the new tour dates on their website.

Kiedis has been dealing with foot problems since the famous Stadium Arcadium tour back in 2007 - recently explaining, "I stayed out on tour with broken bones in my feet from jumping off the bass drum, which is kind of agonising, and it led to me being in a bad state of mind."

The band's website already lists rescheduled dates - with the tour starting in at the Tampa Bay Times Forum on March 29.