Kelly Clarkson has hit back at a social media user who suggested her marriage to Brandon Blackstock “didn’t work” because of her busy schedule.

The singer, 38, urged the critic to “aim higher” after they wrote “no wonder her marriage didn’t work” in response to Clarkson filling in for Simon Cowell as a judge on America’s Got Talent.

Replying to the now-deleted tweet, she said: “Wow. Shaming a woman who has a great work ethic, is a great mom, and who steps up and fills in when a friends asks for a favor because that’s actually what ‘good old country girls’ do….

“This can’t be who you are deep down. I have more faith in your heart. Aim higher please.”

Cowell, 60, is taking time away from work after breaking part of his back in a fall from a new electric bike he was testing at his house in Malibu.

He was taken to hospital where he had an operation on Saturday night, which involved a number of procedures including having a metal rod put in his back.

Simon Cowell recovering after operation
Simon Cowell was injured in a fall from an electric bike (Matt Crossick/PA)

Clarkson filed for divorce from Blackstock, her husband of nearly seven years, in June.

The pair have a six-year-old daughter and a four-year-old son.

They wed in October 2013 in the first marriage for Clarkson and the second for Blackstock.

Blackstock, a talent manager who is the son of Clarkson’s former manager, has two children from his first marriage.