According to the article (2009),“Bone fragments confirmed to be Saint Paul;” Pope Benedict XVI claims that scientific tests confirmed shards found in the underground chamber at the church of St Paul’s-Outside-the-Walls in Rome were from the apostle:
“This seems to confirm the unanimous and undisputed tradition that these are the mortal remains of the Apostle Paul.”
However, the scientific methods only confirm that the bones within the sarcophagus “belong to someone who lived in the first or second century.” The pope accepts the tradition that the bones are from Paul the Apostle and the tests seem to support that possibility.
It should be noted that many of these early Christian traditions have later been found to be spurious particularly early traditions about bones-called relics- of the early Apostles and Saints. If all the supposed relics of the apostles housed in churches across Europe were collected one could probably put together enough bones to represent an entire army.
This does not mean that these relics are not those of Paul the Apostle, only that it cannot possibly be confirmed. It still remains an object of faith and tradition regardless of the statement of Pope Benedict.