Katy Perry and John Mayer partied at a strip club in Las Vegas over the weekend

A source told People magazine "They were together in a group. As for whether they got dances, they were in a strip club ... you do the math.

"The group had so much fun, they stayed until 5 a.m."

Earlier, they were spotted checking into the Wynn Hotel together.

Katy, 27, was thought to have been left heartbroken when John - who has dated a string of Hollywood beauties, including Jennifer Aniston, Jessica Simpson, Taylor Swift and Cameron Diaz - ended their brief fling at the end of August.

A source said at the time: "She is making it seem like it wasn't serious with John, but she is hurt."

Another friend said the 'Teenage Dream' singer - who announced she was to divorce comedian Russell Brand after 14 months of marriage at the end of 2011 - was ready to get serious with John, who she reunited with earlier this month.

They said: "She doesn't want to get her heart broken again, but she feels a real connection and wants to see where things go."

Since splitting with Russell Katy also briefly dated Florence + the Machine rocker Robert Ackroyd in the spring.