Protesters have used legitimate credentials, often obtained from delegates, to get into Madison Square Garden for the Republican National Convention (search), a law enforcement official said Thursday.

"A lot of delegates are just handing them out, and the event people are giving a bunch to different groups," said the official, speaking on condition of anonymity.

Credentials given to delegates were handled by the Republican National Committee. State delegations are got guest passes.

Messages left with RNC officials were not immediately returned.

The law enforcement official said a few protesters entered the arena with guest passes obtained through media organizations. That includes a man brought in by a radio station to be interviewed because his son was killed in Iraq. The man was later seen protesting, the official said.

As Vice President Dick Cheney was speaking Wednesday night, two women from the peace group CODEPINK stood up and unfurled a banner reading "Cheney and Halliburton, making a killing in Iraq," said a spokesperson for the New York Police Department.

Another CODEPINK activist unveiled a banner during first lady Laura Bush's speech Tuesday night. It said, "Be pro-life: Stop the killing in Iraq."

CODEPINK co-founder Jodie Evans declined Thursday to say how the group's activists obtained their credentials, but said the credentials were genuine.

Not all delegations are freely handing out credentials, which have no names or photo identification on them.

"People have to sign up for them, pick them up on specific days and have to show identification," said Brian Nelson, spokesman for the New Jersey Republican State Committee.