The number of Bulgarians and Romanians who migrated to the UK in the year to end-June has increased sharply, contributing to a rise in net migration above government projections, official figures showed on Thursday.

According to the UK’s Office for National Statistics, an estimated 32,000 Bulgarian and Romanian citizens immigrated to the UK in the year ending June 2014, accounting for about 6% of total immigration to the country.

The number of immigrants from Bulgaria and Romania recorded in the year to end-June represented an increase on the 18,000 immigrants from the two countries registered in the previous 12 months and followed the lifting of temporary employment restrictions for Bulgarians and Romanians from 1 January 2014.

“In the year ending June 2014, three-quarters of Bulgarian and Romanian citizens (24,000) migrated to the UK for work-related reasons. This is a statistically significant increase on the year ending June 2013, when 13,000 Bulgarian and Romanian citizens (72% of total inflow from the two countries) migrated to the UK for work-related reasons,” the ONS said.

According to ONS, the number of national insurance registrations allocated to Bulgarian and Romanian citizens seeking work or in employment in the UK skyrocketed n the year ending September 2014. National Insurance Numbers allocated to Romanian nationals increased by 86,000 to 104,000 during the 12 months to end-September, while allocations to Bulgarian citizens grew by 21,000 to 32,000.

The arrival of 32,000 immigrants from the two southeast European neighbours that joined the EU in 2007 increased total net long-term migration to the UK for the year ending June 2014 to 260,000  people  from 182,000 in the previous 12 months.

The Financial Times commented that “the latest data will be a particular blow to the Tories” given that net migration now exceeds the figure of 244,000 registered four years ago when the UK coalition government came to power.

Net migration is the difference between people moving into the UK (immigration) and people moving out of the UK (emigration). If net migration is positive then it means that more people have moved to live in the UK than have left to live elsewhere.

A total of 583,000 people immigrated to the UK in the year ending June 2014, an increase from 502,000 in the previous 12 months.

With long-term emigration levels relatively stable since 2010, an estimated 323,000 people left the UK in the year to end-June 2014, the ONS said.