Tory members under investigation for allegations of Islamophobia will still be able to vote in the contest to pick the next Prime Minister.
Party chairman Brandon Lewis defended the decision to not strip voting rights unless members had been suspended.
He told ITV News there was a "long-standing tradition" in Britain "that you are innocent until proven guilty".
He added: "If somebody has posted Islamophobic comments and is found to have done that, we act swiftly, we would not accept them as a member of the party.
"But let's get the difference between the facts and some of the myth... a lot of the cases that people are saying have been referred to the party, and we've looked into them, are not members of the Conservative Party."
Both leadership contenders are under pressure to commit to a full and independent inquiry into anti-Muslim sentiment in the party.
But neither candidate has unconditionally committed to such a probe.
A poll revealed in the Mirror last week found almost half of Tory party members (40%) believe the Government should "lower the number of Muslims entering Britain."
The results of the YouGov poll for Hope Not Hate also show more than two thirds of those questioned (67%) believe the lie that parts of Britain operate under Sharia law.
The poll shows 45% also believe the falsehood, bolstered by Donald Trump, that there are "no go" areas for non-Muslims in the UK.
The Conservative Party insists it acts "swiftly" to suspend or expel members who post offensive material online.
But according to ITV News, emails show some members are placed under investigation without being suspended.
Those members would retain their voting rights, and would be able to vote in this month's leadership election.
