The biggest single group was Polish with others coming from "new Commonwealth" countries including India, Pakistan, Bangladesh and Sri Lanka.

Of those leaving the UK for a new life abroad, Australia was the favourite destination, followed by Spain and France.

"I think we are seeing something very unusual in world experience," said Danny Sriskandarajah, a migration expert at the Institute for Public Policy Research.

"Britain is becoming a sort of interchange, a hub of the movement of people," he told BBC television.

"There's lots of people moving in and there's also lots of people moving out. That's unlike any other state in the world."

The opening of British borders to new members of the European Union saw a net rise of 64,000 people coming for stays of over a year from countries including Poland, Hungary and the Czech Republic.

The government last month announced it will restrict the influx of migrant workers from Bulgaria and Romania after they join the European Union in January, in a shift from the open-door policy adopted towards other eastern Europeans.

The figures, released by the Office for National Statistics, show 185,000 more people entered the country than left it during 2005.

The net inflow was lower than rise of 223,000 estimated in 2004, but remains the second highest level since current methods of calculation started in 1991.

In 2005, some 565,000 people are estimated to have arrived to live in the UK for at least one year, with 49,000 coming from Poland.

That was offset by 380,000 people leaving the country during the same period.

There was a continued decrease to 11,000 in the net amount of asylum seekers coming to the country, down from a peak net inflow of 81,000 in 2000.

An estimated 60 million people live in the United Kingdom.