ATHENS (AFP) - Greece has received copies of letters by Albert Einstein which suggest that the work of an unheralded Greek mathematician helped shape some of his theories, Greek and Israeli officials said.

Israel's ambassador to Athens, Ram Aviram, presented the Greek foreign ministry with copies of 10 letters between Einstein and Greek mathematician Constantine Karatheodoris, part of a long correspondence which lasted from 1916 to 1930.

According to experts at the National Archives of Israel -- custodians of the original letters -- the mathematical side of Einstein's physics theory was partly substantiated through the work of Karatheodoris, Aviram told AFP.

"The correspondence between the two mathematicians is intensive and quite close," Aviram said. "At a certain moment, they called themselves in private names."

The son of a Greek-born diplomat who served as the Ottoman Empire's ambassador to Berlin, Karatheodoris who was born in 1873 and died in 1950 taught mathematics at four German universities -- including those of Munich and Goettingen -- and also worked on physics and archaeological engineering.

His scientific papers are in the collection of Goettingen University, and have never been translated into Greek, though a number of American universities have copies of his theories, said deputy foreign minister Evripidis Stylianidis.