Spat between leaders of Ukip and French National Front follows Farage's rejection of European coalition offer

This article is more than 6 years old

This article is more than 6 years old

The French Front National leader, Marine Le Pen, has accused Nigel Farage of slander after the Ukip leader called her party antisemitic.

Farage this week rejected a suggestion from Le Pen that Ukip could join a coalition with the FN in the European parliament because of "prejudice and antisemitism" in her party – although he also said Le Pen had "got some good qualities" and was "achieving remarkable things".

But Le Pen used an interview with the Sunday Times to hit back at the Ukip leader, saying Farage had made "defamatory" and "extremely disagreeable declarations" in an attempt to boost his popularity.

The FN leader said Farage was not in a position to cast aspersions on others. "He is often reproached for the behaviour and comments of a certain number of his party members," she said. "Slandering your neighbour to try to make yourself look whiter than white, it's not correct. He's doing it simply for electoral purposes."

The spat with Le Pen comes as Alan Sked, the founder of Ukip, gave an interview in which he described Farage as "alcoholic, dim and racist" and repeated claims – which Farage strongly denies – that the Ukip leader once referred to black people as "niggers".

A Ukip spokesman told the Daily Mail: "Dr Sked is free to hold whatever view he likes of our party and our leader, but his repeated claim that Nigel used the 'n-word' is untrue and has been vigorously denied before."

The rows cap a difficult few weeks for Farage, whose perceived success in two televised debates with Nick Clegg was followed almost immediately by controversy over his claiming of EU expenses.

But a Survation poll in the Hampshire constituency of Eastleigh published on Saturday night showed Ukip would come top in an election there.

The poll put Farage's party on 32% in the former Lib Dem minister Chris Huhne's old seat, with the Tories on 28% and the Lib Dems on 27%. Labour were at 12%.

Survation said this was the "first published constituency-level poll ever to show Ukip in first place". The survey suggests Farage could conceivably use the seat as a springboard into parliament at the 2015 election.

Eastleigh was won by the Lib Dem Mike Thornton with 32% of the vote in a byelection following Huhne's resignation last year, with Ukip's Diane James coming second with 28%.

The latest polling conducted by Opinium/Observer reveals that Ukip has increased its share of the UK vote to 18%, far outstripping the Liberal Democrats at 7%.