Kemi says Immigrants should only be able to apply for British citizenship after being in the UK for 15 years rather than the current six,
She also said indefinite leave to remain, which paves the way for citizenship, should not be granted to those who have criminal records or who had claimed benefits or social housing.
She says the period before someone can apply for ILR should be extended from five to 10 years and people should then have to wait a further five years before seeking citizenship.
It's her first official policy announcement as leader.
The Conservative leader says people shouldn't be able to apply for citizenship for at least 15 years.
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