The chief of the Texas Alcoholic Beverage Commission has apologised for a raid on a gay bar that left one man seriously injured.

The raid was carried out on the Rainbow Lounge in Fort Worth on the 40th anniversary of the Stonewall riots. Customers said they had been harassed and undue force had been used.

Some gay activists have claimed the raid was straightforward discrimination.

Speaking to gay website Dallas Voice, TABC administrator Alan Steen admitted that two officers involved in the raid had committed “clear violations” of agency policy.

He said: “I don’t think you have to dig very deep to figure out that TABC has violated some of their policies. We know that, and I apologise for that. Like I said in my original press release, we have in the past and we will in the future act very swiftly in making sure that those issues are corrected.

“It’s real clear that however it is that we were doing business that night is not the typical TABC. … I have good policy in place, I have good training in place, and I have good supervision in place to ensure that things like this don’t happen.”

The raid was carried out by six police officers and two TABC agents. The TABC agents are on desk duty pending the outcome of the investigation and their direct supervisor has resigned.

Steen added that he thought there was not sufficient evidence for the raid and that permission should not have been granted.

“You can read that policy and you can figure out really quickly, TABC shouldn’t have even been there,” Steen said. “If our guys would have followed the damn policy, we wouldn’t even have been there. … We have these conversations all the time, and we don’t participate in those kinds of inspections when there’s not probable cause or reasonable suspicion or some public safety matter to be inspected.”

He added that he expects to have the results of the investigation within the next few weeks.