Paul Nuttall, UKIP's deputy leader, says any election pact with the Conservatives would be "very difficult" while David Cameron heads up the party.
"You really can't believe a word he says on the European Union and he's also a guy who called us closet racists," he said.
More top news
Sunny and dry for most on Monday although rain affects much of Ireland.
The band returned to the festival - a decade after a disastrous set - as the iconic festival drew to a close on Sunday.
The band dedicated their song Everlast to fan Laura Plane, who died from breast cancer last month.