The Brexit Party has refused to rule out joining a new alliance far-right parties in the European Parliament, fuelling concerns that Nigel Farage could link up with extremist parties once safely re-elected.

Matteo Salvini, leader of Italy’s extreme-right League party, invited Mr Farage’s new outfit to join his group at the weekend, saying he was “waiting for” the arch-eurosceptic.

Brexit Party did not respond to repeated requests by The Independent to clarify whether it would be joining the alliance, which would see it sit alongside Mr Salvini, Marine Le Pen, and other extreme-right parties from across the continent.

Mr Farage previously claimed that he had founded The Brexit Party to escape Ukip’s increasingly extremist direction. The new outfit is leading in the polls ahead of this week’s European Parliament election – despite so far having left voters in the dark about what its policies are on issues beyond EU membership.

“I'm waiting for Nigel Farage. We can work together, I hope,” Mr Salvini told the BBC on Saturday, responding “yes” when asked if he wanted the Brexit Party to join his group.

The Italian interior minister, whose party has provoked controversy with proposals to ban critical academic textbooks and make migrants homeless, added that he would like to link up with the Brexit Party on the issues of immigration and economics.

Guy Verhofstadt, the European Parliament's Brexit coordinator, told The Independent: “It is time for Mr Farage to come clean and rule out a coalition of hate with Mr Salvini and his gang of pro–Russian puppets, who have benefitted from Russia's special war against the West and are a threat to our security and our traditional values.

“Salvini, Farage and their pro–Kremlin extreme right have consistently opposed EU sanctions against Russia. Farage even voted against a European Parliament resolution in March criticising the Kremlin for the Skripal attacks in Salisbury. The British people need to know the truth about their sordid plans for our continent.”

Italian far-right leader Matteo Salvini and Hungary's authoritarian prime minister Viktor Orban in Budapest (AP)

Mr Salvini launched the new group in April to unite popular and far-right groups from across the continent in a single group in the Parliament, with the stated objective of taking control of the EU institutions.

French far-right leader Ms Le Pen said at the time that said she wanted the largest group possible and that Mr Farage was "welcome" in the alliance.

French far-right leader Marine Le Pen (EPA)

Projections based on polling from the EU’s 28 member states suggest that populist, eurosceptic, and far-right groups would form the largest group in the parliament if they united together – but they have so far remained splintered due to political differences and personal rivalries.

Farage launches his new Brexit Party: in pictures Show all 10 1 /10 Farage launches his new Brexit Party: in pictures Farage launches his new Brexit Party: in pictures Nigel Farage speaks at the launch of his new Brexit Party's campaign for the European elections Reuters Farage launches his new Brexit Party: in pictures Brexit Party candidate Annunziata Rees-Mogg, sister of Conservative MP Jacob Rees-Mogg, speaks at the launch AFP/Getty Farage launches his new Brexit Party: in pictures A supporter waits for Farage to speak AFP/Getty Farage launches his new Brexit Party: in pictures Supporters wait for Farage to speak AFP/Getty Farage launches his new Brexit Party: in pictures Farage's socks Reuters Farage launches his new Brexit Party: in pictures Farage and prospective candidate Annunziata Rees-Mogg wait at the launch AFP/Getty Farage launches his new Brexit Party: in pictures Supporters listen as Farage speaks AFP/Getty Farage launches his new Brexit Party: in pictures Free T-shirts for all attendees AFP/Getty Farage launches his new Brexit Party: in pictures Posters on the seats for supporters of the Brexit Party AFP/Getty Farage launches his new Brexit Party: in pictures A safety sign is pictured AFP/Getty

The Italian leader has already recruited the anti-Islam Danish People’s Party, Marine’s Le Pen’s National Rally (formerly National Front), and Germany’s AfD parties into his group, with more expected to follow. It is unclear whether other parties such as Viktor Orban’s Fidesz will join – the Hungarian prime minister currently sits in the mainstream conservative EPP group, though his party has been suspended.