SA MP sorry over bottom slap

South Australian MP Sam Duluk has apologised for slapping another MP on the bottom

A South Australian Liberal MP has apologised and has quit a parliamentary committee after becoming embroiled in a sexual harassment scandal.

Sam Duluk came under fire for his conduct at a pre-Christmas party where it was alleged he slapped SA-BEST upper house member Connie Bonaros on the backside.

He was also accused of sending her unwanted text messages.

On Saturday, Mr Duluk took to Twitter to apologise for his actions.

"I wish to publicly apologise to Ms Bonaros and anyone else who was offended by my actions at a Parliament House Christmas party," he tweeted.

"I'm deeply sorry for any actions that have caused offence."

Mr Duluk said out of respect for the parliament, its staff and his colleagues, he would resign as a member of the Economic and Finance Committee.

Premier Steven Marshall said the MP's behaviour was "completely and utterly unacceptable".

"Sam Duluk recognises this and he deeply regrets the actions of late December," Mr Marshall said.

"He completely and utterly accepts responsibility for his actions."

But Mr Marshall said Mr Duluk remained an excellent local member for the seat of Waite and had made an extraordinary contribution to the parliament since being elected.