The Prime Minister has said victims' lives were ruined by being taken away from the UK and coerced into marriage.
He warned that parents who force their children into an unwanted marriage will face "very tough punishments" under a new law.
The Government is making forced marriage a criminal offence, with Mr Cameron claiming the practice was "little short of slavery".
The Prime Minister added that the issue had been tolerated as a "cultural practice" for too long and the time was right to take action.
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Demonstrators will gather in Lincoln this morning to protest against proposed cuts to the city's local fire service.
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