Ashlee Simpson and Pete Wentz to marry this Saturday

Ashlee Simpson and Pete Wentz are set to get married at a "top secret" location Saturday, according to a report.

The pair, who announced their engagement in April, have not sent out proper invites, "but instead guests have been given a save the date notice," a source tells Us Weekly magazine.

The rehearsal dinner, which will take place Friday, is to be "an intimate affair" for "family and close friends only".

On Saturday, "all guests will be transported in shuttles to the wedding location," the source explained.

Simpson, 23, and Wentz, 28, started dating in late 2006.

The Fallout Boy rocker last month said that he was open to marriage.

"When you find someone you think is your soulmate, it's inevitable," he said.