The Conservatives have been dragged into fresh controversy over Islamophobia after it emerged self-professed party members have been discussing how they could prevent Sajid Javid becoming prime minister.

Tory supporters who claim to be members of the party have attacked the home secretary online for his Muslim background and pledged to back another candidate to prevent any potential leadership bid he might make.

The social media posts, reported by Buzzfeed News, prompted the chairman of the Conservative Muslim Forum to call on the party to do more to promote inclusivity.

One man wrote on Facebook that he had joined the party to help install a Brexiter leader, adding of Javid: “Britain is not ready for a Muslim PM, that would be taking the absolute piss out of the country.”

A woman wrote that she was staying on as a Tory member “so that we can elect the right leader”, commenting that Javid “will protect his own. He was sworn in on the Koran.”

The comments made on Facebook by 20 the self-professed Tory party members are part of a batchunearthed by the anonymous @matesjacob Twitter account, which has been exposing Islamophobia.

Mohammed Amin, chairman of the Conservative Muslim Forum, branded the comments “outrageous”. He said: “The comments from these individuals are deplorable. There are people with bigoted views in all political parties. But a serious question that our party’s leadership needs to ask itself is, what is it about the Conservative party and the way that it’s projecting itself that leads people like these bigots to believe that they have a home within the Conservative party?

“Unfortunately, at the moment I don’t think it’s projecting as inclusive an image of Britain as we did, for example, under David Cameron. It needs to do much more.

“At the moment it’s believed that by dealing with individual instances as they come up that that will make the problem go away and it’s clearly failing. What it needs is much stronger leadership from the top to project a much stronger and more inclusive image.”

It comes amid increasing warnings that the Conservative party is in the grips of a crisis over Islamophobia, with the former party chairwoman Sayeeda Warsi accusing Theresa May of “burying her head in the sand” over the issue.

Lady Warsi, the UK’s first female Muslim cabinet minister, has said the Tories have “turned a blind eye” to prejudice and become “institutionally Islamophobic”.

Other new comments surfacing on Facebook by Tory members include a woman who wrote: “I’m ready to cancel my membership, only holding on to it in case I could use it against them,” adding that “Britain has an Islamic problem”.

The Conservative party would not comment on specific cases, but a spokeswoman added: “Discrimination or abuse of any kind is wrong. When CCHQ [Conservative campaign headquarters] has been made aware of the small number of such cases we have acted swiftly, suspending members and launching immediate investigations, in sharp contrast to other parties.

“Our complaints process is rightly a confidential one, but there are a wide range of sanctions to challenge and change behaviour, including suspension periods and expulsion.”