Image copyright Getty Images Image caption Flight UA 547 was grounded for some four hours over a 'mock' IED

A 58-year-old American has been charged with mischief after US officials found a "mock improvised explosive device" in his suitcase.

The discovery at Toronto's Pearson International Airport sparked a major security investigation.

US Customs and Border Protection called their Canadian counterparts and the mock device was swabbed. No trace of explosives was found.

Travellers on the Illinois-bound flight were delayed for hours and re-screened.

Image copyright Twitter/@customsborder Image caption US Customs and Border Protection thanked Canadian authorities for their assistance

The American was scheduled to take United Airlines Flight 547 on Thursday morning to Chicago's O'Hare International Airport.

Peel Regional Police say the suspect is being held in custody and has a bail hearing scheduled for Friday.

The processing of all travellers in the US pre-clearance section at Pearson, where the mock device was found, was halted while it was tested.

US immigration pre-clearance operations at Pearson allow travellers to pass through US customs sites set up in Canada before landing in the US.

Normal airport operations resumed by midday.