UK Prime Minister Boris Johnson on Wednesday said sorry for the “hurt and offence” caused by incidents of Islamophobia in the Conservatives.
Mr Johnson's apology a contrast with Labour leader Jeremy Corbyn, who failed to condemn claimed anti-Semitism in his party.
The leader of the UK’s Jewish community had said a “poison," sanctioned by Labour leadership, had been allowed to fester.
Mr Johnson and Mr Corbyn are on the campaign trail for a December 12 general election.
“Obviously whenever we have an incident of anti-Semitism or Islamophobia or whatever in the Conservative Party, we take a zero-tolerance approach,” Mr Johnson said.
He pledged to hold an independent inquiry into “every manner of prejudice and discrimination" in the party before December 25.
On Wednesday the Conservatives suspended a candidate in the Scottish city of Glasgow, Flora Scarabello, for alleged use of anti-Muslim language.
“We take allegations like this extremely seriously,” the party said. “There is no place in the Scottish Conservatives for anti-Muslim language, or any other form of racial or religious discrimination.”
When asked if he would say sorry over cases of anti-Muslim rhetoric in the Conservatives, Mr Johnson said: "Of course, and for all the hurt and offence that has been caused. Of course we do.
"All that is intolerable and it's so important as a country that we don't allow that kind of thing, and that's why we're going to have the independent inquiry."
But Mr Johnson failed to clear up his past controversial comments about Muslims. In one instance, he compared women wearing the burqa to “letter boxes” and bank robbers.
On Tuesday night, Mr Corbyn refused to explicitly apologise over accusations that he failed to stop anti-Jewish hatred in Labour.
"What I'll say is this: I am determined that our society is safe for people of all faiths," he told the BBC.
"I don't want anyone to be feeling insecure in our society and our government will protect every community against the abuse they receive on the streets, on the trains, or in any other form of life.
"I want to work with every community, to make sure it's eliminated. That is what my whole life has been about."
A handful of MPs have defected from Labour over Mr Corbyn’s leadership, with the anti-Semitism claims given as a major reason.
He has also been criticised for associating with controversial figures highly critical of Israel, and for showing sympathy towards proscribed terror organisations Hamas and Hezbollah.
On Monday, British Chief Rabbi Ephraim Mirvis said Mr Corbyn was unfit for high office.
