A U.N. convention aimed at ensuring equal rights for the world's 650million disabled people in work, education and social life will go intoforce on May 3, the United Nations said on Thursday.

The pact,the first of its kind, takes effect 30 days after being ratified by 20countries that have signed it. The world body received ratificationdocuments on Thursday from the 20th country, Ecuador.

Astatement issued on behalf of U.N. Secretary-General Ban Ki-moon calledthe development -- 18 months after its adoption by the GeneralAssembly, a short time by U.N. standards -- a "historic moment."

Ban said it showed the world was committed to combatting "the egregiousneglect and dehumanizing practices that violate the human rights ofpersons with disabilities."

The pact would be "a powerful toolto eradicate the obstacles faced by persons with disabilities:discrimination, segregation from society, economic marginalization, andlack of opportunities for participation in social, political andeconomic decision-making processes."

The 32-page conventionoutlaws all forms of discrimination at work on the basis of disability,including in hiring, promotion and working conditions. It requiresequal pay for work of equal value.

It also calls on signatorystates to promote the employment of disabled people, including through"affirmative action" programs that favor them.

The pactstipulates that the disabled may not be excluded from mainstreameducation systems. It demands that states provide them with physicalaccess to buildings, transportation, schools, housing, medicalfacilities and workplaces.

So far, 126 of the 192 U.N. memberstates have signed the convention. But only 71 have signed, and 13 haveratified, an annex allowing individuals and groups to complain to theU.N. that their governments are not implementing the convention.

In such cases, a U.N. committee would refer the complaint to thegovernment concerned, which must provide a written explanation withinsix months.

Countries that have not signed the conventioninclude the United States and Russia. U.S. officials said the documentwas weaker than U.S. domestic legislation.

"We recognize thatmany other states may consider the convention a useful tool as theydevelop their own national framework for persons with disabilities,"said U.S. mission spokesman Richard Grenell.

"But for the U.S.,the Americans with Disabilities Act, passed in 1991, was the mostsweeping legislation to provide access for people with disabilities."