Michelle Brown should be thrown out of the party over comments she made about a Labour MP, UKIP's Welsh MEP has said.
UKIP announced a probe into the matter after a recording emerged of the North Wales UKIP AM using a racial slur against Chuka Umunna in a call in 2016.
But Nathan Gill, who is also an independent AM, demanded immediate action from his party.
Party chairman Paul Oakden said it was his responsibility to ensure due process is followed.
Mr Gill also told BBC Wales he was concerned that the party may come down more heavily on Nigel Williams, the former senior advisor to Ms Brown who had recorded the phone call, and he would not be surprised if UKIP threw him out instead of the AM.
The MEP called the comments "horrendous".
Ms Brown called Mr Umunna a "coconut" and was also recorded using an abusive remark about Tristram Hunt, who was then Labour MP for Stoke-on-Trent Central, in a call to Mr Williams recorded in May 2016.
Mr Williams was sacked by Ms Brown in May.
"She needs kicking out the party," Mr Gill said, saying it was "up to the leadership of the party to set the tone for the rest of the membership and to show what we're really about - that we're not going to tolerate this one iota".
Mr Gill, who was elected as a UKIP North Wales AM but became independent after he left the party in a dispute with assembly leader Neil Hamilton, said: "I am adamant that the party needs to act quickly on this one, that they need to suspend her immediately and that they need to show the rest of the political world what we've been saying for years - that we are not a harbour for... racist comments."
Mr Gill added he was "very concerned" by a statement released at the weekend by the chairman of the party, Paul Oakden, about the case "because it is basically kicking this into the long grass".
In the statement Mr Oakden said it did not condone the views of Ms Brown, and would investigate, but added that the party would also "investigate whether a UKIP member and official surreptitiously recorded a private telephone conversation with Michelle Brown and then disseminated it without her consent, more than a year after the event".
"We're told the National Executive Committee (NEC) are going to be looking at this, but we don't know when the NEC are going to look at this," Mr Gill said.
"I would have thought they could have looked at this immediately today but instead we don't actually have a date they are going to do that, and then it appeared to be more critical of the whistleblower, Nigel Williams, than it did of Michelle Brown and what she actually said.
"I'm very concerned that what we're going to see at the end of this process is the party coming down more heavily against Nigel Williams than it does against Michelle Brown."
Asked if he was concerned that the party may throw Mr Williams out of the party instead of Ms Brown, Mr Gill said: "It wouldn't surprise me in the slightest."
Mr Gill added he was surprised UKIP Welsh assembly leader Neil Hamilton "hasn't publicly condemned and taken the whip off Michelle Brown immediately, because if I was the leader of that group that's what I would have done".
A source close to Michelle Brown said: "If Nathan Gill gets rid of a UKIP AM it damages Neil.
"We know there's no love lost between those two," they added. Mr Gill was beaten to the leadership of the assembly group in a vote last year.
UKIP currently has an interim leader, Steve Crowther, after its previous leader Paul Nuttall resigned after the general election. A leadership election is to take place later in the year.
Mr Oakden said: "It is my responsibility to ensure that due process is followed, as I did when individuals attempted to remove Nathan Gill from the party last year."
It is understood that the NEC is meeting in mid August.
A spokesman for Neil Hamilton said the AM for Mid and West Wales had "no comment".
Ms Brown has previously said that she accepted the language she used "in the private conversation was inappropriate" and apologised "to anyone that has been offended by it".
A spokesman for Ms Brown said it would be inappropriate for her to comment while the investigation is ongoing.
North Wales Police said it had not received any complaints but officers were examining details of the report to establish what criminal offences, if any, may have been committed.