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The final episode of the long-running Australian sitcom Hey Dad! may have long aired, but the show over 7 Network continues to be in the news because of the sexual molestation charges against one of its actors, Robert Hughes.

On Monday, he faced the Downing Centre District Court in Sydney to face child sex offences, marking the start of hearing of evidence against the 65-year-old actor.

His alleged victims are a boy and girls aged 7 to 15. Eleven charges had been filed against Mr Hughes, with a young cast member disclosing that the actor showed his genitals to him on the set and sexually abusing three other girls who slept over at his family home.

The offences were allegedly committed between 1985 and 1990. Mr Hughes has filed a not guilty plea before Judge Peter Zahra.

According to prosecutor Gina O'Rourke, one of the girls allegedly molested was the daughter of the actor's friend. The girl was frightened and crying, leading her mother to confront Mr Hughes.

Another of his female victims was reportedly given a teddy bear after the sexual assault.

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The penis exposure happened near the popular TV show's set at the Channel Seven Eastwood studios in Sydney. The young victim recounted, quoted by ABC, that the actor "pulled down his underpants over his buttocks, exposing his penis."

He then swayed his hips from side to side, causing his penis to sway. He eventually pulled up his shorts and underwear, but by then the young actor had ran and related the incident to another actor.

Mr Hughes, who grew up in Crows Nest, Sydney, denied the charges and claimed he is the victim of constant negative publicity.

His sexual harassment charges came not only from young people but also adult females. One woman claimed that in 1987, the actor rubbed his hard penis against the side of her face while he placed ear drops on her ear. In another instance in 1988, he told a 15-year-old girl he wanted to have sex with her, but he would wait after one year when she turned 16.

Mr Hughes was extradited to Sydney from London in 2012.

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