WASHINGTON - The Obama administration is planning to repatriate six Yemenis held at the U.S. military prison at Guantanamo Bay, Cuba, a transfer that could be a prelude to the release of dozens more detainees to Yemen, according to sources with independent knowledge of the matter.

The release is a significant first step toward dealing with the largest group of detainees at the prison - 97 Yemenis are there - and toward meeting President Obama's goal of closing the facility.

But Yemen's security problems and lack of resources have spawned fears about its ability to monitor and rehabilitate returnees. Critics of the administration contend that returning detainees to Yemen, a country where al-Qaeda is believed to be thriving, is tantamount to returning terrorists to the battlefield.

The six Yemenis, along with four Afghans, will be transferred out of Guantánamo Bay in coming days. The release follows months of high-level meetings between the government in Yemen and senior American officials, as well as a visit to the country last week by Stephen Kappes, the deputy director of the CIA, sources said. The CIA declined to comment.

The transfer will be closely monitored and, if successful, could lead to the release of other Yemenis who have been cleared to go home by a Justice Department-led interagency review team, which examined the case of each detainee held at Guantanamo Bay.

"It's a breakthrough because the U.S. and Yemen governments have been at an impasse," said David Remes, an attorney for seven Yemeni detainees. "Something has broken the logjam, and that's good, because you can't solve the Guantanamo problem without solving the Yemeni problem."

Since the detention center in Guantanamo Bay opened in early 2002, 15 Yemenis who were deemed not to be a threat have been repatriated: 14 by the Bush administration and one by the Obama administration.

The sources, who spoke on the condition of anonymity because of the sensitivity of the matter, declined to identify the latest detainees being released. A Justice Department spokesman would not comment.

Yemenis account for nearly half of the 210 inmates remaining at Guantanamo. Three of those Yemenis have been ordered released by federal judges following proceedings in which they challenged their detention under the doctrine of habeas corpus. Two of those decisions have been appealed by the government.

Although at least 34 Yemenis have been cleared for release, the fate of more than 60 others remains uncertain.

Yemen's government has been struggling with a civil war in the north, a secessionist movement in the south and humanitarian crises as the economy crumbles. In this void, al-Qaeda has steadily grown. U.S. officials are concerned that al-Qaeda could use Yemen as a launching pad for attacks against neighboring Saudi Arabia and in the Horn of Africa.

Yesterday, Yemeni forces, backed by air strikes, said they killed at least two dozen al-Qaeda militants and captured 17 others in a predawn assault on an alleged training camp.

The Associated Press, which quoted security forces as saying at least 34 militants were killed in two assaults, also reported that witnesses put the number killed at more than 60 in the heaviest strike and said the dead were mostly civilians.