MEP Steven Woolfe said his planned speech at the Skainos Centre in Northern Ireland was cancelled at the last minute.
Officials claimed the controversial decision was made because political parties are not allowed to use the facilities, Wolfe said.
But the venue, built with money from the the European Regional Development Fund, hosted a conference for Northern Ireland's Green Party last March.
Sinn Fein's Gerry Adams and Martin McGuinness have also spoken at the venue, which was booked by Ukip's Northern Ireland branch.
Woolfe's speech, on the European Union and migration, was moved to a different venue.
A spokesman for Ukip blasted the cancellation, saying: "This is a blatant attempt to stifle democratic expression of a legitimate national political party representing four million people across this country." Express.
