Geoffrey McGann: 'Artist' carrying homemade 'watch bomb' with fuses and circuit board arrested at California airport

Police claim to have foiled a terror threat after arresting a man as he attempted to board a plane with what they say were bomb-making materials hidden inside a homemade wristwatch.

But Geoffrey McGann claims he is an artist and insists the bizarre timepiece is nothing more sinister than an art project.

The 49-year-old from the Los Angeles suburbs was taken into custody at Oakland Inteational Airport on Thursday night with what appeared to be a potential triggering device for a bomb.

'The watch had on it a toggle switch, a series of fuses, a series of wires protruding from it, a circuit board and the watch itself was on a direct timer,' Alameda County Sheriff's Sergeant J.D. Nelson said.

TSA agents said they became suspicious of McGann when he tried to get the object through airport security by putting it in a bin covered by his jacked.

Sgt Nelson said that was just one of many irregularities which led officers to be disturbed by his demeanour and attire.

'He was wearing a military style shirt that has a built-in touiquet in the sleeves,' he said.

McGannwas also wearing shoes two sizes too big and packed with layers of insoles - an eery similarity to the explosive device wo by the 2001 shoe bomber, Richard Reid.

Suspicious: TSA agents reported McGann placing the wrist watch in a security bin before suspiciously covering it with a jacket that revealed his military-style shirt with a built-in touiquet in the sleeves

Eerie similarities: In addition to his suspicious watch McGann was found wearing shoes two-sizes too big that were stuffed with shoe insoles, much like the 2001 shoe bomber Richard Reid

'They also had what appeared to be a homemade cavity in them and he was very evasive on everything that he was doing,'  Nelson said.

The official said the bomb squad arrived within five minutes and determined there were no explosive materials in the watch.

'Obviously he was missing a couple of things along the way,' Nelson admitted, while insisting police regarded the watch as a possible 'triggering device.'

According to McGann's Facebook page he is managing creative director of a media, marketing and advertising group, having studied visual communication design in college. He is also a father to a little girl.

Asked if the sheriff's department had any idea of a possible motive for smuggling the device onboard, Nelson suggested it was possible McGann was testing out airport security systems in preparation for a full-blown attack at a later date.

'That's always a conce that someone is making a dry run,' he said.

McGann was taken to Santa Rita Jail where he was charged with possessing materials to make an explosive device.