Sarah Harding has insisted her kiss with fellow Celebrity Big Brother housemate Chad Johnson was “a one-off”.

The former Girls Aloud singer and the reality TV star locked lips in scenes which aired on the Channel 5 show on Saturday.

Their secret smooch is revealed to the other contestants in Sunday night’s episode when Sam Thompson tricks Harding into spilling the beans.

Thompson, who did not see the kiss, claims he had seen something when he got up for a drink in the night, teasing: “Sarah, I saw.”

Smiling coyly, she replies: “No you didn’t see anything, I don’t know what you are talking about.”

Chad Johnson in a Celebrity Big Brother promo shot
Chad Johnson (Channel 5)

However, when pressed, Harding admits: “It was a one-off… emotions were very high.”

She then confirms they had kissed.

Thompson starts laughing and shouts: “I knew it! I didn’t even see anything!”

Before she entered the house, Harding told The Sun’s Bizarre column that she was “spoken for” so would not be flirting with anyone.

On Sunday, she tells Johnson she wants to “draw a line” under the kiss as she does not want anyone to get hurt.

She says: “It’s not going to change the fact that we’re friends. I just want to see how things are in the outside world.

“Because one day in here is like a week sometimes. It feels like we’ve known each other for a long time.

“I just feel terrible that I let my emotions get the better of me because my emotions are all over the show in here.

“I just don’t want to make a fool out of anybody.

“I just need to draw a line under what happened last night.

“At the end of the day, you’re single and I’ve only been dating for four weeks and I just don’t want to hurt someone. I just need to respect other people on the outside.”