Gay activists in South Africa have vowed to "flood" the country's blood services with blood donated by gay men.
The blood service says it is following international guidelines
This follows an announcement by the South African National Blood Services that it would not accept donations from men who have sex with men.
The Gay and Lesbian Alliance says its members would lie when asked the question: "Have you had male-to-male sex in the past five years?"
The Alliance claims members have already donated 120 units of blood.
It aims to flood the blood services with 70,000 units.
Alliance spokesman Juan Uys describes the question as "humiliating, offensive and an insult to gay men". He says all blood should be treated equally.
He says the SANBS has already admitted that it uses state-of the art equipment that ensures rigorous screening of donated blood, and therefore they should accept the blood from men who sleep with other men and subject it to the tests.
Mr Uys said the question of risk of HIV infection was no reason to discriminate against gay men.
He says if people were discriminated against based on risk, then South African women between the ages of 18 and 24 should not be allowed to donate, as research shows that they are the group with the highest HIV infection rate in the country.
But the SANBS has described the Alliance campaign as "unfortunate".
Spokeswoman Lanthe Exall says screening procedures are based on World Health Organisation guidelines.
She urged the Alliance to reconsider its actions, which she said posed a risk to the lives of patients needing transfusions.
It is not clear what will happen to blood donated on Friday, as the SANBS will be unable to tell which blood came from Alliance members who lied.
Ms Exall says though they do have the best testing systems in place, no machine in the world can detect the HI virus during the "window period" that follows the transmission of HIV.
It is not the first time that the SANBS has been hit by controversy.
Last year it was forced to change its screening procedures when it was revealed that they destroyed blood donated by black people, because it claimed they were at a high risk of HIV infection.
It emerged that President Thabo Mbeki's blood was destroyed because he was black and because his doctor had refused to complete the personal history questionnaire used to screen donors.
Mr Mbeki donated blood as part of a publicity campaign to persuade people to donate blood.