UKIP's Steven Woolfe and Raheem Kassam to stand for leadership

Steven Woolfe (left) and Raheem Kassam are the first candidates to declare they will stand

UKIP migration spokesman Steven Woolfe and Nigel Farage's ex-adviser Raheem Kassam have declared they will stand as candidates for the party's leadership.

Mr Woolfe, who was barred from standing in UKIP's last leadership election, said the party could replace Labour as the main party of opposition.

Former chief of staff Mr Kassam said he would stop "duplicity" in the party.

They are the first contenders to throw their hats into the ring since Diane James resigned as leader on Tuesday.

The announcements came after Mr Farage announced he would return as UKIP's interim leader until a fresh election could be held to find Ms James's successor.

Ms James announced her resignation after just 18 days in the job, citing professional and personal reasons for her decision.

She succeeded Mr Farage on 16 September after he resigned following the Brexit vote.

• UKIP leadership: The top contenders

• Who is Diane James?

• Chaos returns to UKIP after resignation

Mr Woolfe was barred from standing in the last election after submitting his nomination papers 17 minutes late.

In a statement, he vowed to "stand up for the ignored working class and secure a radically different political landscape in Britain".

The MEP for North West England said he had been tempted to defect to the Tories before deciding to stick with UKIP.

He admitted he had been "enthused" by Prime Minister Theresa May's start to her premiership, citing her support for new grammar schools and her apparent commitment to "a clean Brexit".

"However, having watched the prime minister's speech on Sunday, I came to the conclusion that only a strong UKIP can guarantee Brexit is delivered in full and only our party can stand up for the communities of the Midlands and the north," he added.

"We can replace Labour as the main opposition party."

Mr Kassam, Mr Farage's former chief of staff, who currently edits the Breitbart website, said he was "tired of the chicanery at the top of this party".

He left his role as Mr Farage's adviser following a bout of infighting in 2015.

"There is so much corruption. There is so much duplicity. There are so many people shaking hands with one another and then knifing them in private. It has to stop," he said in a statement.

"I'm clear about what I stand for: a strong, united UKIP, free of the Tory splitters. I want this party to continue to be the driving force behind Brexit."

He added: "I want us to become the real opposition and put this feckless Labour Party to bed."

'Your life finishes'

Earlier, Mr Farage, who was UKIP leader from 2006-2009 and 2010-2016, told the BBC he would continue as the party's interim leader "through the electoral process".

He told the BBC he was "technically still leader of the party" as Ms James's confirmation forms had not been processed before her sudden resignation.

Asked why she had resigned, Mr Farage said he believed it was partly due to a family illness and the "realisation" of what the job entailed.

"When you take this job your life finishes. This is what you are 24/7, there is nothing else. I think she looked down the barrel of that and thought, 'This is not how I want to live my life.'"

Nigel Farage said Diane James's decision to quit was "very difficult"

Ms James, a former businesswoman and healthcare professional, defeated four other contenders - Lisa Duffy, Bill Etheridge, Liz Jones and Phillip Broughton - in the leadership battle.

She won 8,451 votes out of the 17,970 votes cast, ahead of Ms Duffy, who received 4,591.

Former contender Ms Jones said she was also considering standing again.