Comedian Seann and pro partner Katya were snapped seemingly kissing in photos published in The Sun newspaper.
The snaps - taken in the days leading up to Saturday's live episode - see the pair getting cosy on a London street.
Katya is married to fellow Strictly pro dancer Neil Jones while Seann is currently in a relationship with his girlfriend Rebecca.
An onlooker told the newspaper: "They were snogging like a pair of teenagers and didn’t seem to care who might see them.”
Following the publication of the photos, Katya and Seann have both taken to Twitter to issue statements.
Katya wrote: “I’m so sorry about any offence or hurt I have caused with my actions.
“I wasn’t thinking and it was a one off mistake after some drinks.
“I love my husband and we are very happy together, this is not a reflection on our relationship.”
Seann added: "In light of the story in today's newspaper I would like to offer my sincere apologies for my actions.
"This is no excuse but it was a one-off drunken mistake which I am truly sorry for.”
A show source previously alleged that Seann and Katya had "hit it off from day one."
“It hasn’t gone unnoticed by cast and crew but no one expected this," an insider claimed to The Sun. “It’s going to cause real ructions backstage not least because Katya and Neil have to work alongside each other week in, week out."
Both Seann and Katya made it through in Sunday's results to next weekend's show.
Strictly Come Dancing continues Saturday and Sunday night on BBC One.