Net migration to the UK has fallen to the lowest level for three years after a surge in the number of EU nationals leaving the country.
Official estimates show the overall measure - the difference between arrivals and departures - was at 246,000 in the year to the end of March, a fall of 81,000 compared with the previous 12 months.
Statisticians reported that much of the change was driven by an increase in emigration, mainly among EU citizens, sparking claims of a "Brexodus".
The number of EU nationals leaving the UK increased by 33,000 year-on-year to 122,000 - the highest outflow for nearly a decade.
There was a particularly sharp rise, of 17,000, in departures of migrants from the so-called EU8 countries which joined the union in 2004 - Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia.
There was also a 19,000 fall in the numbers arriving from the EU, although this was not "statistically significant".
Total EU net migration was estimated at 127,000, a dip of 51,000 on the previous 12 months. The figure for migration from the rest of the world was also down, by 14,000, to 179,000.
Nicola White, head of international migration statistics at the Office for National Statistics, said: "These results are similar to 2016 estimates and indicate that the EU referendum result may be influencing people's decision to migrate into and out of the UK, particularly EU and EU8 citizens.
"It is too early to tell if this is an indication of a long-term trend."
Liberal Democrat leader Vince Cable said the figures show a "deeply worrying Brexodus of EU citizens who have made the UK their home".
Jonathan Portes, Professor of Economics and Public Policy at King's College London, said the statistics "confirm that Brexit is having a significant impact on migration flows, even before we have left the EU or any changes are made to law or policy".
He added: "EU nationals, both those already here and those considering a move to the UK, are understandably concerned about their future status in the UK."
Net long-term migration estimates reflect the balance between the numbers coming to the country or leaving for at least 12 months.
The overall figure of 246,000 is the lowest since the year ending March 2014.
Lord Green of Deddington, chairman of Migration Watch UK, said: "This is a step forward but it is largely good fortune.
"This should not obscure the fact that migration remains at an unacceptable level of a quarter of a million a year with massive implications for the scale and nature of our society."
Immigration Minister Brandon Lewis said: "The fall in net migration – for the third quarter in succession – is encouraging but we are not complacent. There is still more work to do to bring net migration down further to sustainable levels.
"People who come to our country to work bring significant benefits to the UK, but there is no consent for uncontrolled immigration."
Separate population figures for 2016 revealed that the number of Polish nationals living in the UK has passed the one million mark for the first time.
Last year around one in seven residents were born abroad, while one in 11 had non-British nationality.
Another dataset showed that more than a quarter (28.2%) of births in England and Wales last year were to women born outside the UK, the highest level on record.
Brent in north-west London was the local authority area with the highest percentage of births to non-UK-born women, at 76%.
Labour leader Jeremy Corbyn said the NHS was facing recruitment problems due to the lack of EU workers.
He added: "People move for lots of reasons - our public services would not have survived if there hadn't been a lot of people who had come from all parts of the world and made a massive contribution to all of our living standards."