The country's population rose by 394,000 in 2008-09, according to statistics published yesterday.
The increase is in line with previous years over the past decade, but it is only the second time since 2000 that migration has not been the main cause. In 2008-09, the population stood at 61.8 million, up 0.6 per cent on the previous year, figures released by the Office for National Statistics show.
There were 123,000 more births than seven years earlier, while married women in their 20s and early 30s were more likely to give birth than single women of that age.
Net migration, the difference between immigration and emigration, fell. The population rose by 176,000 as a result of migration, down on the previous year by 15,000. But it is still 23 per cent higher than in 2002, when net migration stood at 143,000.
The Government said it was keen to cut the number of migrants coming to the UK, which stood at 562,000 last year, down slightly on the previous year.
Immigration minister Damian Green said: "We believe that immigration has been far too high in recent years, which is why the new Government will reduce net migration back down to the levels of the 1990s – to tens of thousands rather than hundreds of thousands.
"The public will see us tackle this issue by introducing a wide range of new measures to ensure that immigration is properly controlled, including a limit on work permits, actions on marriage, and an effective system of regulating the students who come here."