The BBC has apologised after viewers saw a weatherman sticking his middle finger up at his co-presenters.
Tomasz Schafernaker, who has posed for gay magazine Attitude, did not realise he was on camera when he made the rude gesture to News 24 anchors Simon McCoy and Fiona Armstrong.
He tried, and failed, to disguise the gaffe by appearing to scratch his chin.
The mishap took place yesterday as McCoy introduced the weather segment.
McCoy said: "Now we'll have the weather forecast in just a minute. Of course it will be 100 per cent accurate and provide you with all the details you could possibly want."
Schafernaker, 31, responded to the joke by sticking his middle finger up, then looked horrified as he realised he had been caught on camera.
As the camera cut back to the news anchors, a gasp was heard and McCoy said: "There's always one mistake."
A BBC spokesman apologised for the incident, saying: "The News Channel presenter in the studio acknowledged a mistake had been made, and we apologise for any offence caused.
"Tomasz was not aware that he was on air, and whilst the gesture was only shown for a second, it was not acceptable."
Schafernaker had to apologise in 2007 after referring to the Outer Hebrides in the Western Isles of Scotland as "nowheresville", while a slip of the tongue last year saw him forecast a "muddy s**te" for Glastonbury festival.
In January, he made headlines by posing for Attitude magazine's supplement Active in skimpy shorts.