Aisam-ud-din, a tribal elder, also said the fighters would only release the other soldiers if their demands were met.
However, Major General Waheed Arshad, a Pakistani army spokesman, denied having agreed to any of the abductors' demands.
"I am not aware of any conditions.
"The release of 26 soldiers have been secured through jirga [tribal council] efforts and in response no militants have been released."
A Pakistani intelligence official said that the fighters were demanding 20 of their comrades arrested in connection with suicide bombings in return for freeing more of the soldiers.
The Pakistani soldiers were captured on August 30 as they travelled in the South Waziristan region.
Earlier this month at least six of the captured soldiers were released.
And on Monday, there were reports that all the soldiers had been freed.
But earlier this week tribal fighters killed at least 16 Pakistani soldiers in neighbouring North Waziristan province, intelligence sources said.
The capture of the soldiers has been an embarrassment for the government of Pervez Musharraf, the president, and came during an increase in attacks on the security forces.
Attacks on security forces and abductions of soldiers have increased in Pakistan's northwest since July when fighters ended a nine-month-old peace deal in North Waziristan and army commandos stormed a radical mosque in the capital Islamabad.
Suicide bombers have also struck near army headquarters in the city of Rawalpindi and at a commando base near Islamabad.
Several hundred people, many of them members of the security forces and fighters, have been killed.