Kutcher apologises for sex case tweets

Hollywood star Ashton Kutcher has apologised after tweeting several uninformed messages about an alleged child sex abuse scandal at a US university.

Kutcher is handing over operation of his Twitter account to his personal management after he tweeted about the firing of Penn State sports coach Joe Paterno.

On Wednesday night, Kutcher defended the American football coach on Twitter before learning the details of the alleged scandal swirling around former assistant coach Jerry Sandusky.

"How do you fire Jo Pa? #insult #noclass as a hawkeye fan I find it in poor taste." Kutcher tweeted.

Kutcher then recanted and apologised on Twitter. He followed with a blog post saying he would have Katalyst Media manage his Twitter feed as "a secondary editorial measure to ensure the quality of its content".

Kutcher, who has more than 8.2 million followers, said Twitter had grown beyond more than "a fun tool". The 33-year-old 'Two And A Half Men' star said the platform has become "too big" for him to manage alone.

The move came as Pennsylvania Governor Tom Corbett asked Penn State students to refrain from violence after rioting wracked their college town following the firing of Paterno, saying the nation was watching their behaviour.

Mr Corbett also expressed disappointment in Paterno and university President Graham Spanier, who were fired by university trustees the night before for their handling of the allegations.

Thousands of students took to the streets on Wednesday night after Paterno's dismissal, overturning a TV news van and throwing rocks, bottles and other objects at police and others.

"I believe in your right of assembly and your right to express your opinions," Mr Corbett said. "I do not believe, nor does anyone believe, in your right to violence."

Investigators said they were reviewing video footage and have identified numerous suspects who could be charged with riot, attempted arson or other counts.

"The crowd initially was a peaceful demonstration against coach Paterno's firing. The crowd quickly turned from a peaceful demonstration to a riotous mob," State College police said in a statement.

"The mob attempted to light vehicles on fire, and tore down light posts and street signs."

Police estimated the crowd totalled 4,000 to 5,000 people and that officers made numerous orders to disperse them but eventually had to use pepper spray.

Paterno had announced earlier on Wednesday that he planned to retire after the season and expressed remorse for not having done more after he learned of sex abuse allegations that had been lodged against former defensive co-ordinator Sandusky, who has denied the charges.

On Wednesday night, the board of trustees announced his immediate firing.