An Indian Muslim preacher has been banned from entering the UK for his "unacceptable behaviour", the home secretary says.
Zakir Naik, a 44-year-old television preacher, had been due to give a series of lectures in London and Sheffield.
Theresa May said that visiting the UK was "a privilege, not a right".
The home secretary can stop people entering the UK if she believes there is a threat to national security, public order or the safety of citizens.
That includes banning people if she believes their views glorify terrorism, promote violence or encourage other serious crime.
However, somebody cannot be banned just for having opinions that other people would find offensive.
Ms May said: "Numerous comments made by Dr Naik are evidence to me of his unacceptable behaviour.
Theresa May No entry: Theresa May has used exclusion power for the first time
"Coming to the UK is a privilege, not a right and I am not willing to allow those who might not be conducive to the public good to enter the UK.
"Exclusion powers are very serious and no decision is taken lightly or as a method of stopping open debate on issues."
This is the first person who has been excluded from the UK since Ms May became home secretary last month.
Mr Naik is based in Mumbai (Bombay) where he works for the Peace TV channel.
He was due to address events at Sheffield Arena on 25 June and Wembley Arena on 26 June.
The BBC's Sanjiv Buttoo says that he is recognised as an authority on Islam but also has a reputation for making disparaging remarks about other religions.
Peace TV itself describes him as "a medical doctor by professional training... and a dynamic international orator on Islam and comparative religion".
"Dr Naik clarifies Islamic viewpoints and clears misconceptions about Islam using the Koran," the channel's website says.
A spokesman for Mr Naik said it was "deeply regrettable" the UK government had "bowed to pressure" from certain groups to exclude him.
He said Mr Naik had been holding talks in the UK for 15 years and the decision to bar his entry was disappointing.
Home Secretary Theresa May said she had barred Zakir Naik, a 44-year-old television preacher based in Mumbai, for inflammatory remarks he was known to have made in the past.
Naik had been due to give a series of lectures in London and the city of Sheffield in northern
"Numerous comments made by Dr Naik are evidence to me of his unacceptable behaviour," May said in a statement, without elaborating.
The Daily Telegraph on Friday reported Interior Ministry sources saying that 2006 website footage had shown Naik telling Muslims it was acceptable to embrace terrorism in certain instances.
According to the paper, Naik said Muslims should beware of people saying Osama bin Laden was right or wrong, adding: "If you ask my view, if given the truth, if he is fighting the enemies of Islam, I am for him.
"If he is terrorising the terrorists, if he is terrorising America the terrorist, the biggest terrorist, every Muslim should be a terrorist."
He is also reported by the paper to have suggested Western women make themselves "more susceptible to rape" by wearing revealing clothing.
"Western society has actually degraded (women) to the status of concubines, mistresses and social butterflies, who are mere tools in the hands of pleasure seekers and sex marketeers," the paper quoted him as saying.
May said: "Coming to the UK is a privilege not a right and I am not willing to allow those who might not be conducive to the public good to enter."
The minister made it clear she had not banned him simply because of his views, which is prohibited under the law.
A Home Office spokesman said the powers were used if an individual expressed views that "foment, justify or glorify terrorist violence in furtherance of particular beliefs" or "seek to provoke others to terrorist acts."
He declined to elaborate on the exact nature of his comments, or when they were made.
I had the "pleasure" of encountering Dr Zakir Naik's views of women and other religions via this YouTube video
sent to me by a friend. He is disgusting and ethnocentric. Every word out of this man's mouth is a crime against humanity. I feel so sorry for the women trapped within that oppressive, sexist religious culture. He actually says that polygamy is acceptable because there are more women than men in the world, with the necessary result that if each man only took one wife, the remaining women would either have to submit to being one of many wives to a single man or would become public property. These are the only two options he gives.
He even says, with disdain in his voice, that it is impossible to choose the best from all religions because there wouldn't be a divine being choosing what is moral and what is not. The dangerous absolute morality of Islam is apparent enough without preachers of hate speech like Zakir Naik. He even goes so far as to speak with disgust about how in some Western cultures it is acceptable to greet a woman by shaking her hand, as though seeing women as equal to men is a grave insult to not just Allah, Muhammad, Islam, and men, but the whole of humanity.
His comments perpetuate terrorism, rape, sexism, religious intolerance, and, as a result, the Islamophobia that has become characteristic of Western cultures. I salute the UK home secretary for taking the initiative to prevent people like him from entering the country. Although I worry that it only serves to widen the divide between Western and Muslim cultures, it is not worth allowing such a gross violator of human rights to spread hatred and victimisation amongst more people than he already has.
There are many in Islam who are seeking to not only change the perception of Islam but also the violence inherent in the Quran. Reform Islam
is a group of Muslims against Sharia law whose goal it is to educate Muslims about inconsistencies in the Quran and the dangers presented by Islamic religious texts, with the conclusion that Islam must be reformed. It is encouraging to see that moderate Muslims are speaking out about fanaticism in their religious culture, but utterly disheartening to think that men like Zakir Naik are reaching more people with their hatred and bigotry every day than moderate Muslim thinkers are.