Forced marriage should be made a specific criminal offence, police say.
A special government unit has been set up to deal with forced marriage
Currently families who compel their children to marry can be charged only with offences like assault or kidnap.
Officers are due to tell a London conference that in the past two years nearly 500 people have asked for help to avoid being forced into marriages.
Metropolitan Police research suggests a link between forced marriage and honour killings and officers say a specific offence would make prosecutions easier.
Honour killings are when people are murdered because they are deemed to have shamed their families and can occur when someone refuses to marry a partner chosen for them.
Police say making forced marriages illegal would send a clear message that this is not acceptable in the UK.
The BBC's Neil Bennett says forced marriages are an under reported problem and it is therefore impossible to say how many young Britons are being pressurised into marriages they don't want.
But he says police figures to be revealed at Monday's conference show that 492 cases have been reported to police forces in England and Wales over the past two years.
Last year, government officials said a special unit within the Foreign Office had dealt with almost 1,000 cases of forced marriage since it was set up in 2000.
It had also rescued and repatriated to the UK 70 young people a year from overseas.
Although the issue is often assumed to affect only women, 15% of cases identified by officials involved men and boys.
A forced marriage is one conducted without the full consent of both parties and under duress.
At present, anyone found guilty of forcing someone into marriage can be prosecuted for kidnap, false imprisonment or rape.