Mr Farage said he was still technically in charge of the party as Ms James’s registration papers had not been processed by the Electoral Commission.
He dismissed suggestions Neil Hamilton - the former Conservative MP and Ukip leader in the Welsh Assembly - could be installed as acting leader by the party’s ruling National Executive Committee (NEC) as “wild speculation”.
“We will have to see about that, won’t we? I find that extraordinarily unlikely. I do not see any prospect of that horror story coming to pass,” he told the BBC’s Victoria Derbyshire programme.
“I have spoken to the Electoral Commission this morning and I am technically still leader of the party as Diane James’s forms did not get processed, so I will continue as the interim leader.”
READ MORE: UKIP in turmoil as leader Diane James resigns after 18 days
The Electoral Commission confirmed it had only received the paperwork notifying it of the change of leadership on Monday of this week and that it had not been processed as there were outstanding questions regarding the completion of the form.
“We are aware that the newly elected leader of Ukip has now stood down and are in touch with the party to confirm how they wish to proceed regarding updating their entry on the statutory register,” a spokesman said.
Ms James’s decision to quit, less than three weeks after she was elected to succeed Mr Farage, threatened to plunge the party into a new round of bitter infighting.
The NEC is expected to hold an emergency meeting in the next few days to decide how to proceed with the leadership contest.
But Mr Farage’s acrimonious remarks about Mr Hamilton suggest it is likely to be a bruising battle, with little love lost among some of the most senior figures in the party.