The Yugoslav government, which denied any such deal, has not acknowledged the release, which took place on Saturday. But William Walker, the chief international peace verifier, said members of his group had witnessed the release.
The Organisation for Security and Co-operation in Europe, which manages the Kosovo peace verification force, welcomed the release as an "act of good will".
"It is the hope of [the verifiers] that this and similar gestures from both sides will help to create an atmosphere conducive to the achievement of a lasting political settlement of the conflict through negotiation," the OSCE said.
But at least two of the released prisoners planned to return to the front lines as soon as possible.
"This is not a crime, this is fighting for the freedom of our country," said Azem Suma, 26.
Sitting in a bombed-out house in Likovac, Mr Suma and another released prisoner, 21-year-old Sahmet Ballazha, said that they had all been beaten and couldn't believe they were still alive.
"I can't explain with words how they treated us. I can't describe the trauma," Mr Suma said as his comrade sat by quietly, looking shell-shocked.
Commanders of the Kosovo Liberation Army told reporters at their headquarters in this central Kosovo village that all nine, including a 16-year-old girl who worked as a military nurse, were generally healthy but showed some signs of having been roughed up.
Meanwhile Western powers will seek to agree this week on a tough new take-it-or-leave-it strategy for halting the conflict in Kosovo, hoping that Russia will agree to back it.
Details of the plan are sketchy, but it appears to centre on a concerted bid to force both sides to accept what they so far have refused to negotiate: Yugoslavia would have to grant self-government or face bombing; Kosovo's Albanians would have to shelve independence demands or go it alone.
How this can be implemented may become a little clearer today, when EU foreign ministers hold regular consultations in Brussels, with Kosovo dominating the agenda.
Four countries from the six-power Contact Group - France, Britain, Germany and Italy - will be represented at the talks.
The fifth and sixth, Russia and the United States, are to hold discussions in Moscow later in the week. (AP)Reuse content