Campaigners are calling for tight restrictions on sexually active gay men donating blood to be relaxed.
Infections can be passed on in donated blood
The National Blood Service says clear evidence shows gay men have a greater chance of passing on HIV and other infections in donated blood.
However, campaigners say there are fewer restrictions on heterosexuals who have high-risk sex.
They want gay men to be judged individually according to their lifestyle, not as a homogenous group.
Currently, blood donated in the UK is screened for a number of bloodborne viruses, including HIV, and hepatitis C.
However, if the donor has been newly-infected with these viruses, there is a "window" in which the tests do not work.
To reduce the risk of contamination, the National Blood Service does not allow sexually active gay men to give blood.
There are also restrictions on intravenous drug users, or heterosexuals who admit "risky" sexual practices involving prostitutes.
Russell Hirst was denied the chance to give blood when his sister was seriously ill.
He said that the ban on gay men was a lifetime ban, while bans on heterosexuals were much shorter.
He said: "I was very shocked when my sister was ill, needed a lot of blood, and I wasn't allowed to donate blood.
"I just want to be equal. Everybody should be judged on their personal activities.
"If a gay man says that he's had unprotected sex with a man, then he should not give blood for 18 months - but I don't see why it should be a lifetime ban."
He said that the reason the ban remained in its current form was to save money for the National Blood Service.
However, a spokesman for the National Blood Service said that the ban was in place "for good reason", and denied there were financial reasons for a ban.
"We ask men who have had sex with men not to give blood because, as a group, they are known to be at an increased risk of acquiring HIV and a number of other sexually transmitted diseases, many of which are carried in the blood.
"While safer sex, through the use of condoms, can reduce the risk of transmitting infections, it cannot reduce this risk to such low levels as to make it totally risk-free."
He said that current donations were enough to meet the UK's needs.
Russell Hirst's campaign, "Bloodban", has started a petition and intends to pass this to Prime Minister Gordon Brown.