A senior Tory peer has called for an independent inquiry into “institutional” Islamophobia in the party.

Former minister Baroness Warsi warned that the party’s failure to address the issue within its ranks risked damaging Conservative chances at the next election.

Lady Warsi, who was the first Muslim woman to have a seat at the Cabinet table, said there was a “deep-rooted problem” in the party and Theresa May had failed to act.

Her intervention came after Tory council candidate Peter Lamb quit after coming under fire for social media comments about Islam.

A total of 14 Conservative members were suspended from the party over allegedly Islamophobic comments on the homepage of a Facebook group.

The Buzzfeed website carried details from the page – established by the self-styled “Jacob Rees-Mogg Supporters Group” – showing posts calling for the closure of all mosques and branding Muslim Home Secretary Sajid Javid a “Trojan horse”.

A party spokesman said: “This Facebook group is in no way affiliated with the Conservative Party and many of the people identified on it are not party members.

“However we have identified some people who are party members and they have been immediately suspended, pending further investigation.

“When we find evidence of members making offensive or inappropriate comments, we consistently take decisive action. Discrimination or abuse of any kind is wrong and will not be tolerated.”

Mr Lamb was due to stand in Harlow, Essex, in May’s local elections despite having been disciplined in 2017.

In 2015, he tweeted: “Islam like alcoholism [sic]. The first step to recovery is admit you have a problem.”

Later in the same year, he tweeted: “Turkey buys oil from ISIS. Muslims sticking together.”

He said: “I deeply regret my remarks on social media. At no point did I intend to cause any offence to the Muslim community. I have reflected on my comments and decided that I should step down as a local election candidate and resign (from) the Conservative party with immediate effect.”

A Conservative spokesman said: “Mr. Lamb was investigated and suspended by his local association back in 2017. He has subsequently resigned from the party.

“Discrimination or abuse of any kind is wrong and will not be tolerated.

“When CCHQ have been made aware of cases we have acted swiftly and decisively, suspending or expelling those involved and launching an immediate investigation under our party’s code of conduct.”

Lady Warsi rejected the claim that the Tories were acting to address the problem.

She told BBC Radio 4’s World at One: “We have a deep-rooted problem of anti-Muslim comments, Islamophobic comments, racist comments that have been made right from the top – from MPs through to councillors, council candidates, members, linked groups.”

She said she had previously suggested an internal inquiry to deal with the issue, but added: “I think it has now gone beyond that and we need an independent inquiry.”

She went on: “We cannot have a situation where a mainstream political party is sending out a message in the way it is acting that certain parts of our country, certain communities in our country, certain citizens in our country, are simply not welcome in our party and therefore are creating this environment in which, sadly, I think we will feel the impact at the next election.”

Lady Warsi urged Tory chief executive and treasurer Sir Mick Davis to act, claiming Mrs May and party chairman Brandon Lewis “have failed”.

Fiyaz Mughal of Tell MAMA, which monitors Islamaphobia, said he met Mr Lewis seven months ago, and he was genuinely committed to tackling hate.

“However, I had made clear that unless affected associations were not supported, provided with training and their systems and processes of weeding out people with hateful views strengthened, then these problems would continue,” he said.

“I impressed on him that some of us within Tell MAMA would even volunteer our time on a personal basis and this was never taken up.

“This problem is not going away unless there is transparency in the process of addressing anti-Muslim hate and where an independent group of people can conduct the activities mentioned on an urgent basis.”

Matthew McGregor, campaigns director of advocacy group Hope not Hate, said: “The Tory’s Islamophobia problem is denial heaped upon wilful blindness. Enough. Suspending a few bad apples won’t cure the rot that seems to have set deep within the party’s membership.

“We salute Lady Warsi for her courage in calling out the problem: it’s now up to Brandon Lewis to move up a gear and launch a full independent inquiry. The problem won’t be wished away or disappear until and unless that happens.”