Update: 8:15am

Modern Family star Sarah Hyland left a Sydney red carpet function in tears after she was allegedly groped by a fan while signing autographs.

The 23-year-old was at The Sebel Pier One in the Rocks on Thursday night with fellow cast members at a red carpet cocktail function when a man allegedly indecently assaulted the actress at about 7.50pm (AEDT).

Witnesses reportedly said Hyland, who plays oldest sibling Haley Dunphy, left the event in tears.

She later took to Twitter to apologise to fans who had been waiting to see her.

“Sorry to all the fans outside the #qantas event that I didn’t get to say hi to but I had to leave due to an inappropriate touch of a fan,” she tweeted.

Her boyfriend, actor Matt Prokop, tweeted his frustration at the “asshole” who allegedly assaulted Hyland.

“All Sarah wanted to do tonight was say hi to the girls who were waiting outside one douche can ruin it for everyone. Goodnight.”

NSW Police said on Friday a 29-year-old Sydney man was arrested on Hickson Road in The Rocks and charged with assault with an act of indecency.

He has been granted conditional bail to appear at Downing Centre Local Court on March 14.