KABUL, Afghanistan — Just months after American officials ceded control over all detention operations in Afghanistan, President Hamid Karzai's government has quietly planned dozens of prisoner releases that American and Afghan officials said on Tuesday would include committed insurgents who had attacked Americans.

The pending wave of releases has revived one of the most caustic — and seemingly resolved — issues between the allies just as relations have hit a new low over Mr. Karzai's refusal to sign a long-term security agreement with American officials. Officials from both countries who support the security deal say they are worried that the mass release of militants with American blood on their hands could scuttle talks altogether and lead to a complete Western withdrawal from Afghanistan in 2014.

It was out of concern that dangerous militants might be too easily returned to the battlefield that American military commanders initially resisted Mr. Karzai's demands in the spring to hand over all detention operations. As the Americans relented, they said they had received his personal assurances that security would be maintained.

Suddenly, it is a major issue again, though the releases have not been made final.

The Afghan commission charged with reviewing detainee cases at the main military prison near Bagram Air Base, a coalition hub north of Kabul, is planning to release more than 85 prisoners who the coalition and Afghan defense officials say should face trial. The plans were detailed by American and Afghan officials alarmed by the move, and have been confirmed by commission members.

"These are guys that are tied directly to killing and trying to kill our forces and Afghan forces," an American military official said. "This is an issue of deep concern. It is serious."

The commission disagrees. Abdul Shakor Dadras, a member of the three-man panel, said there was no real evidence against any of the men, who are among the 650 prisoners the panel has ordered freed since it was created by Mr. Karzai after the transfer of the prison in March.

In an interview on Tuesday, Mr. Dadras said that Mr. Karzai tentatively approved the releases at a cabinet meeting last week. The president, he said, ordered the commission to give the international military coalition and the main Afghan intelligence agency until Friday to produce evidence against the detainees. If none is produced, the men will be released, Mr. Dadras said.

But American and Afghan security officials, who spoke on the condition of anonymity because of tensions between the countries, said they had already given the commission enough evidence to send all the detainees in question to trial, or at least to hold them pending further investigation. The officials said they have evidence linking the detainees to the killings of 117 American, European and Afghan service members and civilians, and that they are ready to continue investigating in cases where more evidence is need to try the men.

One of the detainees was caught planting a hidden bomb and was linked by biometric evidence to other bomb attacks that killed two Afghan soldiers, the officials said. Another is alleged to have trained and deployed teenage boys for suicide attacks. A third placed a hidden bomb outside a school, killing a student, the officials said.

Both the Afghan defense officials and the Americans argued that under the deal that transferred control of the prison, the commission did not have the authority to order the releases over the objection of the coalition and the intelligence service, which is supposed to make a recommendation on each case.

The commission "has exceeded its mandate and ordered the release of a number of dangerous individuals who are legitimate threats and for whom there is strong evidence supporting prosecution or further investigation," said Col. David Lapan, a spokesman for American forces in Afghanistan.