Ashlee Simpson and Pete Wentz to wed this week

Ashlee Simpson will wed Pete Wentz in a secret ceremony on Saturday (17.05.08).

The 'Pieces of Me' singer and the Fall Out Boy rocker – who got engaged last month – have told guests to keep the day free although they have not let anyone know where the nuptials will take place.

A source told Us Weekly magazine: "Proper invites have not been sent out but guests have been given a save the date notice."

On Friday (16.05.08), close friends and family will join the couple for a rehearsal dinner.

The following day, guests "will be transported in shuttles to the wedding location".

Ashlee's spokesperson has refused to confirm or deny the rumoured nuptials, saying: "This is a private matter. There is nothing to confirm."

Ashlee and Pete announced their engagement last month, saying: "Yes, we are thrilled to share that we are happily engaged. Thank you for all of your support and well-wishes - it means the world to us."

It was later reported Ashlee was pregnant with the couple's first child and are keen to tie the knot before the baby is born. A source said: "They're keeping it quiet because they want to get married first."