Net migration to Britain reached 318,000 in 2014, its highest level since 2005,
There were increases in both EU and non-EU migration, with 318,000 people moving to the UK in 2014.
It comes as the Conservatives unveil new plans to seize the wages of illegal workers as proceeds of crime in an attempt to reduce the numbers.
Prime Minister David Cameron said it had become “too easy” for migrants not entitled to be in the country to exploit loopholes.
The data comes hours before Cameron unveils new laws to deter migrants from coming to Britain, and a day before he meets other European leaders to tentatively set out plans for a renegotiation of the country's ties with the EU.
Cameron has pledged to win reforms in Europe, including changes to how easily EU migrants can access his country's welfare system, before giving Britons an in-out EU membership referendum before the end of 2017.
The Office for National Statistics data showed a net 318,000 people moved to Britain in 2014, against 209,000 in 2013. It called the rise "a statistically significant increase," saying it was just below a previous peak of 320,000 in 2005.
Since Cameron promised in 2010 to get net migration down to the 'tens of thousands' - an acknowledgement of public concern about the impact of rising immigration - the regular data release has been seized upon by political rivals as a reminder of the difficulty of controlling migration from the EU.
Britain's economy, which is performing better than most of the EU, has made the country an increasingly appealing destination for those seeking work.
