MPs could be sued for tweets

Speaker Bronwyn Bishop has warned federal MPs that parliamentary privilege might not cover defamatory tweets.

Labor MP Jim Chalmers was absent from the House of Representatives on Monday after being suspended last week for calling Prime Minister Tony Abbott a "pathological liar" during question time.

The Queensland MP was forced to leave the chamber but repeated the remark in a tweet afterwards.

"Time and time again Tony Abbott has proven to be a #pathologicalliar - Triggs, pensions, SBS, health, ed the list goes on and on," he wrote.

After investigating the matter, Mrs Bishop said no action would be taken against Mr Chalmers for the unparliamentary language.

But she warned all MPs against tweeting inside or outside the chamber because it was unlikely to be covered by parliamentary privilege.

It could expose them to the possibility of legal action, she said.

Mr Chalmers was later granted parental leave for the remainder of the parliamentary sitting period.