Katy Perry and John Mayer split? (From Burnham and Highbridge Weekly News)

Katy Perry and John Mayer split?

10:24am Wednesday 20th March 2013 in National Entertainment News © Press Association 2013

Katy Perry and John Mayer have split for a second time, according to reports.

Us Weekly said that Firework singer Katy, 28, and John, 35, have gone their separate ways.

The pair began dating last summer, and briefly broke up in August before getting back together a month later.

"It's sad," a friend was quoted as saying, but added: "It's not over until it's over. You have to see how things play out."

Another source said: "She's leaving the window open. They have both been so focused on work."

Katy, who divorced comedian Russell Brand last year, recently prompted speculation that she was engaged to singer-songwriter John, after being spotted leaving a Valentine's Day dinner with a ring on her engagement finger.

But friends were reported to have denied the rumours, saying that the ruby was a commitment ring.