Kaley Cuoco denies romantic reunion with Johnny Galecki

Kaley Cuoco has dismissed speculation her close relationship with ex-boyfriend and TV co-star Johnny Galecki led to the breakdown of her marriage to Ryan Sweeting.

The Big Bang Theory star announced she was ending her 21-month union to tennis player Ryan last month (Sep15) and she subsequently filed for divorce, citing irreconcilable differences for the split.

Tabloid reports have since alleged Kaley is back in Johnny's arms, but on Wednesday (14Oct15), the 29 year old moved to dispel the rumors.

"So sorry to disappoint, but no home wreckers or secret flings going on here," she wrote alongside an Instagram snap of the actors smiling and bumping fists. "Me and (Johnny) are just the best of buds".

Referring to their newlywed TV characters, she added, "Leonard and Penny will just have to suffice!!!"

Johnny, 40, also posted a similar snap, which he captioned, "No scandals / home wreckers / pregnancies here, y'all. Just profound friendship."

She previously dated Johnny for two years before their break-up in 2010, but they have remained good friends.

Kaley and Ryan wed on New Year's Eve, 2013, and just days before her split announcement, she insisted her husband and her ex had become pals.

She said, "We dated, like, five years ago so I think we've both moved on... Johnny is actually one of my best friends. It's a situation that ended well... Ryan loves him, Johnny loves (Ryan), it's been a long time, so it's great. I got lucky."