The co-chairman of the Conservative Party in Britain says prejudice against Muslims has become widespread and socially acceptable in Britain.
Baroness Sayeeda Warsi is the first Muslim woman member of a British government.
She says anti-Muslim prejudice is now seen by many Britons as normal and uncontroversial, and she plans to use her position to fight an ongoing battle against bigotry.
In extracts of the speech, published in the Daily Telegraph, she blamed the patronising, superficial way faith is discussed in certain quarters, including the media, for making Britain a less tolerant place for believers.
And she said terrorist offences being committed by a few Muslims, are being used to condemn the whole community.
Baroness Warsi also revealed that she raised the issue of Islamophobia with Pope Benedict XVI during his visit to Britain last year, urging him to create a better understanding between Europe and its Muslim citizens.
The BBC's religious affairs correspondent says Lady Warsi has broached the issue before.
She told a Conservative Party conference in 2009 that anti-Muslim hatred had become Britain's last socially acceptable form of bigotry, and claimed in a magazine article last October that taking a pop at the Muslim community in the media sold papers and didn't really matter.