The Muslim Council of Britain (MCB) has renewed its call for an independent inquiry into accusations of Islamophobia in the Conservative Party, accusing it of failing to act.
In a letter to the Equality and Human Rights Commission, the MCB accused the party of a reluctance to address what it said was a "systemic" problem.
The Conservative Party said it takes a "robust approach to discrimination".
The commission said it was "actively considering" what action it might take.
The EHRC - the UK's human rights watchdog - also said it was "awaiting the final terms of reference of the party's independent review which we will consider as part of our decision making process".
The MCB, which is an umbrella organisation of various UK Muslim bodies, first wrote to the equalities commission in May last year saying there was "sufficient evidence" to suggest the party may have breached anti-discrimination law.
Now it has submitted an updated document to the Equalities and Human Rights Commission, saying it was "regrettable" no action had been taken and citing further instances which it said showed anti-Islam sentiment was prevalent within the party.
The allegations include comments said to have been made by some MPs which the MCB claims are "anti-Islam" and contribute to a "toxic culture" in the party which makes Muslims feel unwelcome.
The document cites the instance of Tory MP Daniel Kawczynski being reprimanded by the party, but not suspended, for appearing at the same conference as far-right figures, including Hungary's nationalist Prime Minister Viktor Orban and and Italy's ex-deputy PM Matteo Salvini.
At the time, the MP for Shrewsbury and Atcham defended his participation saying that although he didn't agree with all their policies "they represent serious ideas and concerns".
The MCB's document also raises the case of Conservative MP Karl McCartney who apologised after retweeting posts from supporters of former English Defence League leader Tommy Robinson.
The group has also compiled a list of dozens of incidents of Conservative councillors or representatives allegedly sharing Islamophobic content online, as well as more than 180 similar incidents involving people claiming to be party members - some of which have been previously reported.
Responding to the MCB's document, the Conservative Party said it "consistently takes decisive action to deal with any incidents of hatred, abuse or intimidation".
"We are holding an independent review which is looking at how we can improve our processes - to make sure that any instances are isolated, and that there are thorough processes in place to stamp them out as and when they occur."
In December, the party announced Professor Swaran Singh would lead an independent review into the Conservative Party's handling of all forms of discrimination and prejudice.
The then-Tory chairman James Cleverly said: "The Conservative Party will never stand by when it comes to prejudice and discrimination of any kind."
The MCB has accused the party of "reneging" on a promise to hold an independent inquiry specifically into Islamophobia, accusing the party of failing to take direct and appropriate action on the issue.
It comes after the Equalities and Human Rights Commission launched an investigation into anti-Semitism in the Labour Party, in December last year.
Labour has said it is fully co-operating with the investigation but had improved its internal processes to deal with anti-Semitism allegations.