A Portuguese historian believes he has solved the age-old mystery surrounding the nationality of Christopher Columbus.

According to Manuel Rosa, a lecturer at Duke University, North Carolina, the explorer was in fact the son of Polish King Władysław III.

It has always been thought that King Władysław III fell in battle against the forces of the Ottoman Empire at the Battle of Varna in 1444. According to Mr Rosa, however, the king managed to survive the battle unscathed and fled to the Portuguese island of Madeira where he lived out the rest of his life as a hermit and married a Portuguese noblewoman.

It was there that the exiled king bore a son – or so Mr Rosa's theory goes – who would later be credited with the discovery of America. In Mr Rosa's opinion, a conspiracy was in place to protect the identity of Columbus' royal father.

“The courts of Europe knew who he was and kept his secret for their own reasons,” he told The Daily Telegraph.

Mr Rosa says that he has uncovered a plethora of evidence lending support to his theory. First, the explorer's last will, which read “being I born in Genoa,” was apparently forged after Columbus' death. Secondly, the explorer's coat of arms is similar to that of the Polish king. And thirdly, he had "reddish-haired, fair skinned and blue eyed – all features commonly found in Poland.”

The historian is hoping to clear up the mystery by collecting DNA samples from Poland's dead kings and comparing them with the DNA of Columbus' son who lies in rest in Seville Cathedral.

“I have made a request to the Cathedral in Kraków to examine remains from the tomb of Władysław II, who could turn out to be the grandfather of Columbus. It would prove the truth of my theory,” said Mr Rosa.

It is a commonly held belief among historians that Columbus was born in Genoa, Italy, to Genoese parents. Some have said, however, that he was actually born in Spain.