document: Arron Banks, who funded the Leave EU campaign in last year's EU referendum, made the allegation via Twitter.
  He said the move was "apparently" in response to him saying the party's current leadership "couldn't knock the skin off a rice pudding".
  But a spokesman said his membership had lapsed earlier this year.
  And party leader Paul Nuttall said the businessman - who has suggested he should be made party chairman to shake up the party's policymaking and campaigning - was causing "negative and damaging publicity".
  In a letter to Mr Banks, Mr Nuttall said the party's ruling NEC had agreed to meet the businessman later this month to discuss his ideas but this invitation could be withdrawn if he continued to criticise UKIP and its leadership.
  He added: "I should make clear that, whilst I am open to working with you on improving and enhancing our party, the party chairmanship is not on offer."
  Mr Banks, who gave Â£1m to the party ahead of the 2015 general election, has been sceptical about the leadership of Paul Nuttall and has recently spoken of founding a new political movement to "drain the swamp" of Westminster politics.
  He also suggested he could stand against Douglas Carswell, UKIP's only MP, by using a recall petition to trigger a by-election in his Clacton constituency.
  But Mr Carswell played down the importance of Mr Banks' announcement, telling the BBC: "It's always very sad when one of UKIP's 40,000 members leaves the party for whatever reason."
  Referencing previous claims that he had prevented former UKIP leader Nigel Farage from being knighted, Mr Carswell added: "I have no more say in NEC decisions at UKIP than I do in who gets a knighthood."
  On Mr Banks' suggestion that he could stand against Mr Carswell in Clacton at the next general election, the MP said: "Each time I've stood there've been some wonderfully colourful characters on the ballot paper.
  "I even had a chap who changed his name by deed poll to Lord Ha Ha Woof Woof. I'm sure at the next election there'll be some colourful characters too - the more the merrier."
  Apology to squash clubs
  But in a statement, Mr Banks claimed UKIP had "somehow managed to allow my membership to lapse this year despite having given considerably more than the annual membership fee over the past 12 months".
  "On reapplying I was told my membership was suspended pending my appearance at a NEC meeting," he said.
  "Apparently, my comments about the party being run like a squash club committee and Mr Carswell have not gone down well.
  "I now realise I was being unfair to squash clubs all over the UK and I apologise to them. We will now be concentrating on our new movement."
  However, a UKIP spokesman said Mr Banks was notified last year that his membership was due for renewal at the start of October but he "chose not to renew despite reminders".
  "With this his membership expired on 1st January 2017," the spokesman said. "It would not be possible to suspend Mr Banks from something of which he is not a member."
summary: The UK Independence Party has rejected claims by one of its biggest donors that he has been suspended from the party membership.