Police in the US state of California have announced the arrest of a man at a security checkpoint near a campaign rally for Republican presidential candidate Donald Trump.

The detainee faces weapons charges after loaded guns were found in his possession, as well as several passports and a fake licence plate, according to the local police chief.

Riverside County Sheriff Chad Bianco suggested that authorities may have thwarted an assassination attempt, but made it clear that the hypothesis was still ‘speculation’.

A federal official confirmed that a federal investigation into the incident is underway, while jail records showed that the suspect was released on bail on Saturday.

Trump narrowly escaped an assassination attempt last July when a bullet passed close to his ear during a campaign rally in Butler, Pennsylvania.