Rachel Riley has threatened legal action against Twitter users following a row over her comments on anti-Semitism in the Labour Party.

The Countdown co-presenter and the former EastEnders actress Tracy Ann Oberman are preparing to sue up to 70 people for alleged libel and harassment, according to their lawyer Mark Lewis.

Twitter users had been sharing and commenting on an article published by political blogger Shaun Lawson, which accused Riley and Oberman of harassing and slandering a 16-year-old Labour supporter who was involved in an online debate.

Riley and Oberman have repeatedly clashed with Labour supporters, particularly over Jeremy Corbyn's handling of anti-Semitism allegations within his party's ranks.

Earlier this year Riley accused Mr Corbyn of "giving a legitimate voice to Holocaust denial" and "sharing platforms with terrorists" during an interview with Channel 4 presenter Krishnan Guru-Murthy.

Mr Lewis has sent public messages to scores of Twitter users, informing them that he is being instructed by Riley and Oberman to take legal action against them and asking them to email him their contact details by 1 March.

If they fail to reply, he writes, he will seek a court order to obtain their addresses so he can serve the legal action.

He adds: "In the event that my clients are put to such expense it will add to the costs being sought from you. So that you are aware of your obligations I must inform you that I have screenshots of your tweets. Deleting Tweets without preserving Twitter Analytics is a very serious matter."