More women are being sent on international assignments than ever before, but they are far less likely to be accompanied by a partner than male assignees, according to a survey by Mercer Human Resource Consulting.

Companies in Asia-Pacific said they have 16 times more females on assignment this year than they did in 2001. Companies in North America have nearly four times as many, while those in Europe have over twice as many.

Yvonne Sonsino, principal at Mercer Human Resource Consulting, says: "The huge growth in the number of females sent on assignment by Asia-Pacific companies reflects the fact that businesses in this region, particularly in China, are becoming increasingly global."

Over half of the companies (55%) expect the number of female assignees to continue to increase steadily over the next five years, while 35% believe the number will remain the same, just 4% believe it will decline.

"Going on expatriate placements can be an important step on the career ladder, and women are increasingly interested in taking these assignments. Yet many companies' policies are outdated and do not reflect the changing profile of their expatriates, so assignees' requirements are dealt with on a case-by-case basis," adds Sonsino.

Though the companies surveyed generally do not have separate policies for female expatriates, the study found some differentiation in the treatment of male and female assignees. For example, 15% of companies said they would not send women to sensitive locations such as the Middle East.