Updated

Sen. John Kerry called on the government Thursday to abolish a "discriminatory" law that bars homosexual men in the U.S. from donating blood, saying "not a single piece of scientific evidence supports the ban."

In a letter sent to the Food and Drug Administration, Kerry, D-Mass., along with a host of other Democrats, urged Commissioner Margaret Hamburg to change existing law that bars gay men from giving blood.

Kerry also called on the FDA to review its donor screening questionnaire to ensure a healthy blood supply.

"A law that was once considered medically justified is today simply outdated and needs to end, just as last year we ended the travel ban against those with HIV," Kerry said in a statement on Thursday.

Under the current law, which went into effect in 1983, any man who has had a sexual relationship with another man since 1977 is prohibited from donating blood.

In an op-ed published Wednesday in Bay Windows newspaper, Kerry called the ban a "cruel reality that I thought warranted a close examination of the justifications.

"The three largest blood donation organizations in our country -- the American Red Cross, America's Blood Centers, and AABB (formerly the American Association of Blood Banks) -- all agree calling the ban 'medically and scientifically unwarranted,'" wrote Kerry.

Gay rights group have also decried the practice both in the United Kingdom and the United States. The Gay Men's Health Center reported last month that the ban was created at a time when the transmission of HIV was unknown and creates a stigma that is inconsistent because straight people who have sex with "commercial sex workers" only have to wait a year before donating blood.

The group adds that the chronic shortages of blood should be proof enough that limiting gay donors is self-destructive.

Part of the shortage may be due to the fact only three of every 100 Americans donate blood, according to the American Red Cross. The agency has a long list of eligibility rules on its Web site.

Click here to read Sen. Kerry's op-ed.