NEW YORK (AFP) - A US Air Force veteran has been charged on two counts for trying to join ISIS extremists in Syria after being sacked as a plane mechanic, prosecutors announced Tuesday.

Tairod Pugh, 47, from New Jersey, travelled from Egypt to Turkey in January in an attempt to cross the border into Syria to join ISIS (Islamic State in Iraq and Syria), but was intercepted and sent back to Egypt, prosecutors said.

After he was deported back to the United States, US agents impounded his laptop and allegedly discovered he had been watching ISIS propaganda and browsing the Internet on how to infiltrate Syria.

He was arrested on January 16 and faces a maximum 35 years in prison if convicted of attempting to provide material support to a foreign terrorist organisation and obstruction of justice.

A federal grand jury in Brooklyn indicted him on both counts Monday and he is scheduled to appear before a magistrate Wednesday.

His alleged attempt to join Syrian extremists came weeks after he was sacked from his most recent job as an airplane mechanic based in the Middle East, federal prosecutors said in Brooklyn.

He served previously in the US Air Force as an instrument specialist and was trained in aircraft engine, navigation and weapons systems maintenance, the prosecutors said. US reports said Pugh served in the US Air Force from 1986 to 1990.

"Born and raised in the United States, Pugh allegedly turned his back on his country and attempted to travel to Syria in order to join a terrorist organisation," said US Attorney Loretta Lynch.

"We will continue to vigorously prosecute extremists, whether based here or abroad, to stop them before they are able to threaten the United States and its allies."

Last Friday, three New York residents pleaded not guilty to terrorism charges connected to another aborted attempt to travel to Syria and join ISIS.