Music mogul Simon Cowell is said to have presented his girlfriend Mezhgan Hussainy with a huge diamond ring which he placed on her engagement finger.

Cowell, 50, surprised his girlfriend with the giant rock as they dined alongside his old flame Jackie St Claire and her husband Carl Michaelson at Mr Chow in Knightsbridge, London.

The X Factor judge is said to have declared he had a special announcement before pulling out the diamond sparkler and placing it on the ring finger of Afghan-born Hussainy, 36.

“Simon may come across as Mr Nasty on screen but he’s a big softie at heart,” the Mirror quoted a source as saying.

“He wanted to do something unexpected and out of character on Valentine’s Day and decided to splash out on a ring.

“Mish was speechless and gave him a huge kiss. He is besotted with her, and she him,” the source added.