The wreckage was found on Sunday in the jungles around Mullaittivu, the last stronghold of the Liberation Tigers of Tamil Eelam (LTTE), and officials were investigating if it was a part of the Tigers' air force.
"We have asked the air force to examine the wreckage and find out if it is a Tiger plane or parts of an air force aircraft downed inside LTTE-held areas some years ago," an official said.
The makeshift jungle runway was the sixth of its type to be overrun by government soldiers, who are rapidly advancing on areas in the north once controlled by the LTTE, according to the military.
The Tigers are believed to have five Czech-built Zlin-143 aircraft, smuggled onto the island in pieces and re-assembled.
The guerrillas last launched an air attack early in September, when they bombed a military base.
Army chief Lieutenant General Sarath Fonseka said on Saturday that he believed the guerrillas still had at least three aircraft and one airfield left.
The rebels are