Immigration to rich countries dropped during the global economic crisis, reversing five years of annual increases as the demand for labor fell, the Organization for Economic Cooperation and Development said Monday.

A report showed that 4.4 million people migrated to the OECD's 31 member countries — the world's most developed economies — in 2008. That is a drop of about 6 percent from the year before.

The fall reverses five years of annual increases of 11 percent, the OECD said in its International Migration Outlook 2010.

National data suggest that international migration fell again in 2009.

Unemployment among male immigrants has risen more than among native counterparts because many immigrants worked in industries badly hit by the crisis, such as construction, hotels and restaurants, the OECD said. Still, few are returning home, it said.

In some countries, employment of female immigrants has risen as women take jobs to make up for lost income of their unemployed spouses, it said.

Law firm merger activity picked up after a sluggish first quarter in part due to a renewed increase in transatlantic marriages between large domestic firms and those headquartered in England.

Among the 10 mergers reported last quarter by legal consultancy Hildebrandt Baker Robbins -- one more than during that time frame last year -- was the union of Washington stalwart Hogan & Hartson and London-based Lovells to form Hogan Lovells, which the report characterized as the second-largest since Hildebrandt began tracking quarterly merger activity.

A second cross-border marriage of equals, between Chicago-based Sonnenschein Nath & Rosenthal and London's Denton Wilde Sapte, was announced last quarter but is not included in that figure because the merger will not be completed until later in the year.

Industry analysts say that after a period of caution, U.S. firms are once again looking for markets in which to expand -- and the obvious one for some is London, where many firms specialize in the kind of corporate transaction work that has long been the bread and butter of New York.