This is a dangerous time to be a black African in Libya.

Throughout the conflict that began in February, rebel forces have been rounding up suspected mercenaries whom, they say, have been hired from neighboring countries like Chad and Niger to fight for Col. Muammar el-Qaddafi.

But Libya has a black population of its own, and many black migrant workers were trapped in the country when the conflict began. And it seems that plenty of the black Africans captured as mercenaries were never actually involved in the fight.

On Monday, the chairman of the African Union, Jean Ping, said that Libya’s Transitional National Council “seems to confuse black people with mercenaries,” as my colleagues Kareem Fahim and Neil MacFarquhar reported. (There are documented cases of mercenaries from elsewhere, including an ethnic Croatian named Mario who was interviewed in Time magazine last week.)

Amnesty International issued a statement on Tuesday saying that people suspected of fighting for Colonel Qaddafi, “in particular black Libyans and sub-Saharan Africans, are at high risk of abuse” by rebel forces. The statement said that Amnesty representatives were told on recent visits to detention centers in al-Zawiya and Tripoli that one-third to half of the detainees there were from sub-Saharan Africa.

Alex Thomson, a reporter for Channel 4 News in Britain, recounted a frightening scene he witnessed in Tripoli, where men captured by the rebels insisted they were not mercenaries. Those men, he said, appeared to be in serious danger — and they also appeared to be telling the truth.

“Please,” they begged us, “please don’t go. Don’t leave us. They will kill us.”

Another just asked me: “Will they shoot us? Please tell me Sir. Will they shoot us?”

Herded into a corner, a gunman started slapping them. We asked him to stop.

“They are with Gaddafi. We know this. They had guns.”

“Show me the guns,” I said.

No guns arrived. Some of the men crossed themselves, sweating, praying. One began weeping softly.

Mr. Thomson said the men eventually led the rebels to “their women” who were hiding in the bush nearby. Satisfied that they would not have brought their wives to fight in the war, the rebels let them go.

“To be a black African in the wrong part of town at the wrong time,” Mr. Thomson concluded, “is to be in a very frightening place.