TORY leadership candidate Andrea Leadsom is facing a “black-ops” campaign by MPs who want to “denigrate her reputation”, leading supporter Iain Duncan Smith has claimed as the election to succeed David Cameron descended into increasing bitterness and rancour.

The fall-out continued from a row which erupted after Leadsom was accused of suggesting that having children made her a better choice of leader than frontrunner Theresa May who is childless.

Backers of May ramped up their attacks on Leadsom, with one senior minister suggesting she could become the Tory equivalent of Jeremy Corbyn because of her lack of support in Parliament.

Employment minister Priti Patel, who campaigned for Brexit alongside Leadsom, claimed that the energy minister lacked the experience and broad appeal to win a general election.

Business minister Anna Soubry was also reported to have called on Leadsom to quit the leadership contest, saying she was clearly not “PM material”, adding it would “do us all a favour including herself”.

But former Tory leader Duncan Smith insisted both candidates are capable of becoming the next prime minister and called for the Conservative Party to show “decency” during the campaign.

Asked about reports that some MPs are prepared to quit the party if Leadsom becomes prime minister, he told ITV’s Peston on Sunday: “I have a simple comment to them, which is calm down for God’s sake, this is a leadership election and I think people come to regret some of the silliest things they say during a leadership election.

“I’ve seen it all before – the reality is that both of them are qualified.

“Look, if Andrea was so unqualified to be prime minister, and you know we’ve had a lot of sniping, a kind of real ‘black-ops’ operation to denigrate her reputation.”

He later added: “We should really be very careful about the threats and the things that we say, all of us, and conduct this in decency.”

The SNP said the exchanges exposed the attitudes of two right-wing politicians with a “track record of extremely regressive policy positions” and with “little regard for Scotland’s interests”.

SNP MSP Joan McAlpine said: “The depressing spectacle of the Tory leadership contest so far has only showed how out of touch their party is with opinion in Scotland – and made clear that no matter who wins, Scotland will lose.”

Senior Tories traded blows after Leadsom was reported to have suggested she had a greater “stake” in Britain’s future than her childless rival May.

In an interview, Leadsom said: “Genuinely I feel that being a mum means you have a very real stake in the future of our country, a tangible stake.”

The Home Secretary has previously spoken about how she and husband Philip were affected by being unable to have children.

Duncan Smith suggested the interview was a “stitch-up” and Leadsom has insisted she was “disgusted” with the way that her comments had been presented and said she did not want the issue of children to be a feature of the campaign.

However, the row failed to die down, with Conservative MP Tim Loughton telling the BBC that the energy minister’s comments showed her passion for her family, adding: “That’s what fires her up”.

Tory MP Patel, who is backing May’s campaign, warned that Leadsom could find herself unable to govern due to the lack of support from MPs, or win an election victory by appealing to swing voters.

In an interview, she said: “We have to govern. To govern we have got to be able to carry the support of Members of Parliament. That’s incredibly important. I don’t need to give a re-run of what’s happening with Labour right now.”

Asked if Leadsom could become a Conservative version of Corbyn, Patel said: “We could end up in that situation.”