JOHOR BARU • A man has been arrested for reportedly showing threatening and vulgar hand signs to the Sultan of Johor's motorcade convoy in what is likely to be the first case of its kind in the state.

The 40-year-old suspect, who has not been identified by the media, was in his car as Sultan Ibrahim Sultan Iskandar and his convoy passed by him on the North-South Expressway on Sunday morning, The Rakyat Post reported on its news site.

The sultan was on his way back to Johor Baru after visiting the royal town of Muar.

The suspect allegedly lowered his window and showed a fist and also a lewd sign at the passing royal convoy which caught the attention of the Johor ruler.

The man was quickly arrested by the police after Sultan Ibrahim ordered for action to be taken against the motorist, who later claimed he was unaware that the ruler was in the car at that time.

"The suspect is under police custody and will be investigated under Section 506 and 509 of the Penal Code for criminal intimidation and words or gestures intended to outrage the modesty of a person," Johor police chief Wan Ahmad Najmuddin Mohd said yesterday.

Meanwhile, police are investigating two men under the Sedition Actfor allegedly insulting the Sultanate of Johor and the royal family, the Bernama news agency reported.

Datuk Wan Ahmad Najmuddin said police found photographs of Sultan Ibrahim and Crown Prince Tunku Ismail Idris which were allegedly uploaded to Facebook by the second suspect.

It is not clear exactly what the two men did, but Mr Wan Ahmad Najmuddin warned the public against spreading "slander-laced statements" on social media to smear the name of the royal family.

The two suspects face a jail term of three years each.