Kate Beckinsale and Jack Whitehall have been spotted kissing.

Kate Beckinsale

Kate Beckinsale

The 45-year-old actress and the 30-year-old actor were seen sharing a passionate smooch at a Los Angeles karaoke bar on Friday (02.11.18) night, before heading back to a hotel together in the early hours of Saturday morning.

A source told The Sun on Sunday: "No one would expect someone like Jack to bag one of Hollywood's hottest actresses. You couldn't get a more unlikely romance.

"They were like a pair of loved-up teenagers and weren't trying to hide their feelings.

"They were practically sitting on top of each other in the booth of the nightclub and were laughing with each other.

"Then he decided to put his hand around the back of Kate's neck and pulled her across him, where they started to passionately kiss.

"Kate then half-laid across him as they whispered to each other. Then they decided to make a quick exit."

The pair were not trying to hide their tryst, as they started off their evening with a dinner at celebrity hotspot Craig's.

Although they left the restaurant separately, Kate picked Jack up in her SUV and they headed to the Blind Dragon karaoke bar, which is also frequented by celebrities.

And they ended their night at the flashy London hotel.

Jack and his long-term girlfriend Gemma Chan ended their six-relationship in December, while Kate - who has 19-year-old daughter Lily with her former partner Michael Sheen - split from Len Wiseman in 2016 after 12 years of marriage.