Jo Marney reportedly sent a series of messages to a friend, in which she claimed Ms Markle’s “seed” would “taint” the royal family.
The 25-year-old reportedly branded Prince Harry’s fiancée a “dumb little commoner” who is “obsessed with race”, The Mail on Sunday reported. She was also said to have claimed that their marriage was paving the way for a “black king”.
A Ukip spokesman said the glamour model had been suspended from the party.
Ms Marney told the newspaper that she wanted to “unreservedly” apologise for the ”shocking language” she used in the messages.
“The opinions I expressed were deliberately exaggerated in order to make a point and have, to an extent, been taken out of context. Yet I fully recognise the offence they have caused,” she said.
The Independent has approached Ukip for comment but none had arrived at the time of publication.
Ms Marney’s suspension comes as 54-year-old party chief Mr Bolton faces an investigation by senior Ukip officials into his private life that could put his future as party leader at risk.
Mr Bolton had already faced calls to resign after left his wife Tatiana, 42, with whom he has two children, to begin his relationship with Ms Marney. He has insisted the pair did not get together until after his separation but the revelations have sparked a backlash among some party activists.
In a letter to members, Ukip chairman Paul Oakden said the national eecutive committee ruling body had agreed to discuss the issue at a special meeting in January. He wrote: “Both the committee and the Leader understand the strength of feeling on this coverage and are keen to work collectively in finding a resolution that best protects the future prospects of Ukip.”
Former Ukip leadership candidate Ben Walker has called for Mr Bolton to resign immediately, accusing him of having “deeply flawed judgement”.
“Go now @_HenryBolton,” he wrote on Twitter: “You have destroyed your own family; don’t destroy our political one too.”
Mr Bolton was elected as Ukip leader in September, beating controversial anti-Islam activist Anne Marie Waters.