Reform UK’s parliamentary candidate in Kemi Badenoch’s constituency has resigned after it emerged he previously urged people to vote for the BNP.

Grant StClair-Armstrong, the party’s candidate in North West Essex, told BBC News he had “never supported the BNP” and had been forced to stand down by the party.

“I would have let the people decide,” he said.

But a spokesman for Reform UK said “Mr StClair-Armstrong has tendered his resignation” after “the revelation of unacceptable historic social media comments”.

In remarks first reported by the Times, Mr StClair-Armstrong wrote on a website: “I could weep now, every time I pick up a British newspaper and read the latest about the state of the UK. No doubt, Enoch Powell would be doing the same if he was alive. My solution … vote BNP!”

Mr StClaire-Armstrong told BBC News he posted the comment sometime between 2004 and 2007 and he was an “angry man” at the time.

“I have never supported the BNP. I think they are a disgusting organisation,” he said.

Asked whether he had chosen to resign, he said the party had forced him to.

“To be honest I wouldn’t have stepped down. I would have let the people decide.”

Mr StClair-Armstrong will still appear on the ballot paper as the Reform UK candidate because the deadline for nominations has passed. But if he is elected he would stand as an independent.

The Times reported his comments on the website also included racial slurs as well as a joke about “female hormones”.

According to the paper, on a blog he called the “Joli Triste” Mr StClair-Armstrong wrote about the Scottish politician, Kenny MacAskill, wishing serious illness on them.

On the Chilcot inquiry into the Iraq war, he wrote: “The simple solution is to extradite Blair … [and] the odious Alistair Campbell to a country that routinely indulges in torture and execution”.

Speaking on Sunday, he said: “I bitterly regret all of those comments made many years ago and I am just sorry that some people deemed it necessary to hunt for them when I am not the person I was then.”

A spokesperson for Reform UK said: “Mr St Clair-Armstrong has tendered his resignation as a member of Reform UK due to the revelation of unacceptable historic social media comments and we have accepted his resignation.”

The list of candidates standing in North West Essex:

• Kemi Badenoch – Conservative
• Erik Bonino – Independent
• Edward Gildea – Green
• Andrew Green – Independent
• Niko Omilana – Independent
• Smita Rajesh – Liberal Democrats
• Grant StClair-Armstrong – Reform UK
• Issy White – Labour