LONDON - Around 200,000 more people are likely to come to Britain to live, work or study than leave the country next year, keeping net migration broadly unchanged from recent years, a think-tank said on Thursday.

Ministers have pledged to cut net migration, the difference between those entering and leaving the country, from the hundreds of thousands seen this decade under the former Labour government to "the tens of thousands" by 2015.

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The government says it cannot absorb the equivalent of twice the population of the city of Birmingham being added every decade.

"Reducing net migration by more than half would be a challenging task for any government, at any time, but it is made harder in the UK by the fact that government has no, or limited, control over some major immigration flows," the Institute for Public Policy Research (IPPR) said in a briefing.

Therefore, to meet its reduction target, the government will have to more than halve immigrant numbers in those categories over which it does have control. This is mainly immigration from outside the European Union for the purposes of work or study, the think-tank noted.

In November, ministers cut the number of skilled workers allowed to enter from outside the European Union by a fifth, capping the number at 21,700 from April next year.

But the cap will only reduce overall migration numbers by 2 or 3 percent, the IPPR said.

In relation to immigrant students, it added: "Significant reductions in numbers will only come at the expense of fee income for the UK's higher and further education sectors.

"The government plans to curb foreign student numbers substantially, but the restrictions are not likely to take full effect in 2011."

One of the biggest flows that the government can do little about is the movements of EU nationals, many more of whom are immigrating to Britain than emigrating from it.

They accounted for around a fifth of total net migration in the year to March, according to provisional data from the International Passenger Survey.

"If the UK economy continues to perform more strongly relative to eurozone countries, Spain, Portugal and Greece, we might expect increased net inflows from the EU - which is not covered by the annual cap being introduced in April," the IPPR said.

"Increased inflows from Ireland - where the economy is in severe trouble - are likely."

Likewise, the government has no control over the in and outflows of British citizens. Many fewer Britons are now emigrating, which has had "a major impact" on net migration numbers this year, the think-tank said.

In the year to March, 31,000 more Britons left the country than arrived here, compared with 80,000 in the previous 12 months and 132,000 in the year to March 2007, according to the International Passenger Survey.

The IPPR attributed the decline to the global recession and a weaker pound and added: "There is no obvious reason why this trend should change sharply in 2011."

"The government also faces legal limits on its ability to reduce asylum flows to the UK, or to restrict the ability of British people or settled migrants to bring their families to the UK," the IPPR said.