NEW YORK (AFP) - Women are closing the gender gap on men in health and education but still cannot get a firm foot in the political and business doors, an international study said Tuesday.

Women hold less than 20% of key national positions, said the World Economic Forum in its Global Gender review of 135 nations.

While 85 percent of the countries have made some progress in the past six years, women's rights are declining in the rest of the world, notably in several African and South American countries.

International scores for health and education have improved with 96% of the health benchmarks and 93% of the education gaps closed. Economic and political participation continue to show the largest gaps.

Less than 20% of ministers and national lawmakers are women, said the report. There are about 20 elected female heads of state and government.

According to the report, a fifth of the countries surveyed have mandated female company board representation and 30% have mandated political participation.

"A system where women are not represented at the highest levels is both an unequal and inefficient system," said WEF founder Klaus Schwab and report co-author Saadia Zahidi said.

Nordic countries still dominate the WEF gender equality rankings. Iceland, Norway, Finland, Sweden and Ireland were the top five. Yemen ranked at the bottom of the 135-nation table with Chad, Pakistan and Saudi Arabia just in front.

The sixth annual report showed a slight decline over the last year for New Zealand, South Africa, Spain, Sri Lanka and Britain. Notable gains were made by Brazil, Ethiopia, Qatar, Tanzania and Turkey.

The United States came 17th. France was top ranked for education and health but lost points on economic and political influence and came 48th overall.

China came third-to-last in the ranking on health and survival due to a skewed sex ratio at birth. But it was boosted by having about three quarters of its women in employment and ranked 61st overall.

Brazil moved from 85th to 82nd with the fast rise in incomes and after Dilma Rousseff's election as president.

The report can be consulted at: http://reports.weforum.org/global-gender-gap-2011.