More than 150 people have been prevented from giving blood at an event in Belfast, Northern Ireland(NI) aimed at encouraging people from the Indian community to donate.
Srikant Ganapati from the Sudarshanam charity said people had taken time off work to attend the event.
However, he said they were all told because they were born in India, they were not able to donate.
The NI Blood Transfusion Service said it was investigating what happened.
They said they welcome everyone who gives blood but said there was strict donor eligibility criteria.
Mr Ganapati said it was arranged nine months ago that members of the Indian community would donate blood and that their ethnicity was known by the NI Blood Transfusion Service.
He said those taking part were not informed in advance that they would need a malaria test to assess suitability before coming to the donation session in north Belfast last Friday.
Mr Ganapati said they only found out about the criteria when they turned up at the venue.
“They said to me, ‘are you born in India?’, I said yes. ‘Did you recently visit India?’, I said no, I have not been there for the last four years,” Mr Ganapati said.
“He said, ‘if you born in India, you have to do a malaria test’.”
When he asked how long it would take to get the results of a malaria test, Mr Ganapati said he was told between six and eight weeks.
He described what had happened as “very frustrating” for all those from the Indian community, most of whom had taken the day off work to attend.
“Most of the Indians here are professionals, some are nurses and doctors, they all gave their time to support this blood donation, but unfortunately they all had to leave frustrated,” he said.
Mr Ganapati said they should have been informed before they arrived but said that all of those who turned up were willing to submit to a malaria test and hoped to be able to donate blood at a future date.
The event had been organised by the Sudarshanam charity which promotes Hindu and Indian culture in Northern Ireland.