Net migration to Britain has fallen to a three-year low as a growing number of European Union citizens have left the country following last year’s Brexit referendum.

Data released Thursday by the Office for National Statistics provides evidence that the uncertainty and economic jitters caused by Britain’s vote to quit the EU are deterring immigrants and sparking a “Brexodus.”

The statistics office said net migration — the difference between arrivals and departures — was 246,000 in the year to March 31, a fall of 81,000 on a year earlier. More than half the change was due to a decline of 51,000 people in net migration from the EU.

A total of 122,000 EU citizens left Britain in the year to March, up 31,000 from the year before and the highest outflow in nearly a decade.

There was a particularly sharp rise in departures from citizens of the “EU 8” — the eastern European nations that joined the bloc in 2004. Hundreds of thousands of Poles, Lithuanians and other eastern Europeans moved to Britain to work after 2004.

EU citizens have the right to live and work in any member state, and more than 3 million nationals of other EU countries reside in Britain.

When Britain leaves the EU in March 2019, it will have the power to set restrictions on the movement of people from the EU, leaving many EU citizens uncertain about their future rights in Britain.

Nicola White, head of international migration figures at the U.K. statistics office, said the figures “indicate that the EU referendum result may be influencing people’s decision to migrate into and out of the U.K., particularly EU and EU8 citizens.”

“It is too early to tell if this is an indication of a long-term trend,” she said.

A fall in the value of the pound since last year’s referendum and a slowdown in the British economy may also be making the country less attractive to migrants. The statistics agency confirmed Thursday that the economy grew by a modest 0.3 percent in the second quarter of 2017 from the previous three months, slower than any other Group of Seven economy.

Pro-EU opposition politicians and business leaders said the decline in migration was an early-warning sign, and Britain would face a shortage of workers if it severely restricted immigration after Brexit.

Matthew Percival, head of employment at the Confederation of British Industry said the loss of “vital skills” should concern everyone in Britain.

But Prime Minister Theresa May’s Conservative government, which has a longstanding and unmet pledge to cut net immigration below 100,000 a year, said the figures were “encouraging.”

“People who come to our country to work bring significant benefits to the U.K., but there is no consent for uncontrolled immigration,” said immigration minister Brandon Lewis.