Justin Bieber's father has been joking about the star's penis after naked pictures of him were published.

Following the publication of images of Justin, 22, nude on holiday in Hawaii, his dad Jeremy, 41, took to Twitter to write ''My boy'' along with a cactus emoji.

Although he deleted that tweet, Jeremy went on to share a picture of his native Toronto's CN Tower on Instagram and tagged Justin in, with fans believing he was making a reference to the size of his son's penis.

He then took a picture of himself beside the tower and, once again, tagged Justin in.

This isn't the first time Jeremy has bragged about his son's size.

Last year the singer threatened to take legal action after three full frontal nude photographs of him taken while he was on holiday with Jayde Pierce in Bora Bora surfaced online but Jeremy didn't appear too concerned.

He took to Twitter to praise the 'Where Are U Now' hitmaker's manhood, tweeting: ''@justinbieber what do you feed that thing. #proud daddy (sic)''.

While Justin was initially very unhappy and felt violated by the images, a source claimed that he cooled off after they went viral because he thinks they are very flattering.

The Canadian heartthrob's personal-trainer Patrick Nilsson previously claimed he was ''well-endowed'' despite reports his Calvin Klein underwear campaign had been photoshopped to give him a bigger package.

He said: ''I can definitely confirm that he is a well-endowed guy. I sound weird saying that, but yes.''

Justin was also forced to defend his physique after he was accused of relying on photoshop when he appeared topless on the cover of Men's Health magazine.

He tweeted at the time: ''I love the fact that I got in shape the past two years, and I'm finally getting recognition for it. It's not photoshopped for all you fools out there saying it's photoshopped.''