More than 60,000 immigrants from eastern Europe registered to work in Scotland over the past four years, according to a report published yesterday.

The study, by the Institute for Public Policy Research, revealed that around one million people had moved to the UK from countries such as Poland, Lithuania and Slovakia since 2004. But the think-tank said that around half of the migrants had already returned to their home countries and more were expected to follow.

A total of 765,690 migrants registered to work in the UK between 2004 and 2007, including 62,440 in Scotland. Two-thirds of all approved applications between May 2004 and December 2007 were from Polish nationals.

However, the institute said that the numbers were starting to fall, with 17% fewer people registering to work in the second half of 2007 than in the same period of 2006.

Dr Danny Sriskandarajah, head of migration research at the Institute of Public Policy Research and report co-author, said: "Our findings challenge the widely held assumptions that most of those who have arrived are still here, that more will come and most will stay permanently.

"It is a question of when, not if, the great east European migration slows. With fewer migrants in and more migrants out, the UK seems to be experiencing turnstiles, not floodgates."

Liam McArthur, Liberal Democrat Enterprise spokesman, said: "Scotland has done well in attracting migrant workers, who have made a real contribution."

It was a concern to certain industries that the flow of workers was tailing off, he added.