Slayer has postponed its U.K. and European tour until spring 2010.

Instead, Slayer will co-headline the "American Carnage" tour with Megadeth early next year. Kicking off on January 18 in Seattle, Wash. for a 26-date trek across North America, the "Carnage" tour will include the six Canadian dates postponed earlier this month.   Testament will be billed as special guests for the entire tour.   "American Carnage" is the first time that Slayer and Megadeth will have toured the U.S. together since 1991's "Clash of the Titans" tour, and will sell a portion of the tour tickets at the "1991 price" of $10.00. Tickets for most shows go on sale this Friday, Nov. 20.

The band announced the European and U.K. tour cancellation with "immense disappointment" in a statement, blaming a back injury sustained by vocalist/bassist Tom Araya that has required specialist treatment.

"Right now, our main concern must be the full and permanent recovery of Tom, so we have decided to clear the calendar and give him the extra time he needs to concentrate solely on good health," said manager Rick Sales.

The tour was due to begin in the U.K. on Nov. 18 and conclude on Dec. 17 in Germany. It has now been rescheduled to kick off on March 7 in Manchester, England.