Fifty Arabs who were abducted and then secretly transferred to prisons in Kurdish-dominated northern Iraq have been released as part of an agreement between Kurdish and Arab political leaders and the U.S. military, Arab officials announced Friday.

Abdullah Sami, an Arab member of the provincial council in the northern city of Kirkuk, called the release a "first stage" and said the agreement called for all detainees who had been illegally transferred to Kurdish-held prisons to be released or brought before judges outside the Kurdish region.

The release of the detainees would "help cool down the situation," Sami said, referring to tensions between Arabs and Kurds around Kirkuk.

For months, security forces led by Kurdish political parties have escalated a campaign to seize hundreds of Sunni Arabs, Turkmens and members of other minorities from such cities as Kirkuk and Mosul and then transfer them illegally to a network of prisons in Kurdistan, the semiautonomous Kurdish region. Some detainees were tortured, according to accounts by prisoners and police.

One recently released prisoner, Muhammad Shihab, said Kurdish authorities hid detainees when representatives of the International Committee of the Red Cross inspected detention facilities.

Sami said the two largest Kurdish political parties, the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK), agreed to release the detainees under pressure from American officials and the U.S. military. He said the agreement was forged under the supervision of Brig. Gen. Alan Gayhart, commander of the 116th Brigade Combat Team, which is responsible for security in Kirkuk.

The released detainees were held for six months to a year, Sami said. Thirty of them were released from the prison in the city of Irbil controlled by the KDP, he said, and the other 20 from a PUK-controlled prison in Sulaymaniyah. The KDP previously released 42 detainees from Irbil following pressure by the U.S. military, but the PUK had been unresponsive, according to military officials.

In June, a State Department cable said the "extra-judicial detentions" had "greatly exacerbated tensions along purely ethnic lines" and endangered U.S. credibility in the region.

U.S. officials in Baghdad said they had no immediate information about the agreement. However, officials said it would be consistent with American diplomatic and military efforts to pressure Kurdish authorities to practice due process of law and maintain respect for human rights.

Kurdish officials were unavailable for comment. Earlier, they acknowledged that prisoners had been transferred to Kurdistan but denied participating in any extra-judicial abductions or arbitrary detentions.

The total number of detainees is not known, but some U.S. officials and Arab leaders have estimated it to be in the hundreds.

Accounts from the recently released detainees were consistent with previous reports of abuses.

Shihab said that during his detention he and other prisoners were "exposed to insults and psychological pressure" by Kurdish authorities. The detainees were told never to talk about their treatment, Shihab said. He said the majority of the detainees were from Kirkuk, Mosul and Tikrit and were jailed in private houses that held approximately 75 prisoners.

"We did not know where we were at," he said.

Another released detainee, Muhammad Awad, said he believed he was arrested because he had been an intelligence officer in the Iraqi military. Awad said he was detained in Kirkuk during a joint operation by U.S. forces and the Kurdish-run Emergency Services Unit, a 500-member anti-terrorism unit within the Kirkuk police force.

Awad said he was kept in solitary confinement for four months.