The UK has moved closer to overtaking France as the second most populous country in the European Union, official figures show.
As of January the two nations had an estimated 65.8 million and 67 million inhabitants respectively, according to data published by the EU's statistical agency Eurostat.
The figure for the UK, which currently has the third highest population in the union, saw an annual rise of more than 400,000 - meaning it has narrowed the gap to France in second to just over 1.2 million.
In 2016, the difference between the two countries was close to 1.4 million, while in 2010 it stood at more than two million.
Last month separate figures revealed that the population of the UK had seen its sharpest annual increase in nearly 70 years, reaching 65.6 million in the middle of 2016.
Official projections have suggested the country will surpass Germany and France to become the most populous in the EU by the middle of the century.
Overall, the population of the EU was estimated at 511.8 million at the start of this year, compared with 510.3 million in January 2016, with all of the change attributed to net migration.
The Eurostat report said: "During the year 2016, as many births as deaths were recorded in the EU (5.1 million), meaning that the natural change of the EU population was neutral.
"The population change (positive, with 1.5 million more inhabitants) was therefore due to net migration."
Germany remains the most populous member state, with 82.8 million residents, accounting for 16.2% of the total EU population - followed by France (13.1%) and the UK (12.9%).
Population increases were recorded in 18 states, while there were falls in 10, the Eurostat report said.
Alistair Currie, head of campaigns at the charity Population Matters, said: "These figures underline the sustainability problem that we are facing across Europe.
"As Europeans, our relentless consumption, from cars to coffee, is placing a strain on our environment and resources, here in Europe and beyond.
"On a domestic level, while our place in the population league table is of only symbolic importance, the UK will soon overtake France with less space to put our people into.
"Immigration is the main driver of our growth but amid ongoing Brexit uncertainty, the most recent figures have shown a decrease in net migration from Europe.
"We simply do not know how this will pan out following our discussions with the EU. What is clear is that we must develop an integrated, effective and realistic policy framework for population."
He called for the Government to introduce a national population policy to "advocate managing population growth in a fair and sustainable way".