Israeli Prime Minister Benjamin Netanyahu's Likud Party has released a new campaign trying to paint his main rival, former military chief Benny Gantz, as mentally unstable.

The video ads are the latest move in a campaign that has been heavy on personal insults and short on substance. Elections are scheduled on April 9.

Likud has tried to capitalize on Gantz's fumble in two television interviews last week, by publishing a video with extracts zooming in on the former general's wide-eyed look with the signature violin screech from Alfred Hitchcock's "Psycho" playing in the background.

Recent polls have placed Gantz's Blue and White party ahead of Netanyahu's Likud. Gantz's campaign has stressed his security credentials — an important quality with the Israeli electorate.