The Human Rights Campaign on Monday issued an apology for its treatment of transgender and immigration rights activists during rallies supporting marriage equality outside the U.S. Supreme Court last week.

The nation’s largest LGBT advocacy group had come under fire after reports that an unnamed HRC staff member had harassed an activist who was waving a transgender pride flag, asking him on several occasions to move or stop displaying the flag in order to keep out of the scope of TV cameras.

One report, by a companion activist who was waving the bisexual pride flag, said the HRC staffer told the activist, “this is about marriage equality, not the Trans community.”

In another complaint, a undocumented LGBT activist was asked to edit his speech to hide his immigration status.

Initially, the HRC denied the allegations, and said, “It is not true to suggest that any person or organization was told their flag was less important than another – this did not occur and no HRC staff member would ever tolerate such behavior.”

But on Friday, after Bilerico co-founder Jerame Davis reported that he witnessed the altercation, the United for Marriage Coalition (which includes the HRC), acknowledged the incidents and said “apologies are being made individually and collectively and we are working to make direct amends.”

Earlier Monday, HRC Vice President of Communications Fred Sainz issued an additional apology, saying, “To be perfectly clear, HRC regrets the incidents and offers our apologies to those who were hurt by our actions. We failed to live up to the high standard to which we hold ourselves accountable and we will strive to do better in the future.”

The incident has reopened old wounds among longtime activists that the HRC has not been sympathetic to transgender issues.

In 2007, the HRC supported a version of the Employment Non-Discrimination Act (ENDA) that excluded transgender individuals from the anti-discrimination bill.