Papua New Guinea's Opposition says Prime Minister Michael Somare has "lost the plot" after swearing at them in parliament and refused calls to stand down.
During heated exchanges on the floor of the house, Somare called Deputy Opposition Leader Bart Philemon a "bastard" and even called for him to step outside to sort things out.
He later withdrew his remarks.
Mr Philemon told reporters the prime minister seemed to believe he had an overwhelming mandate after recent elections and could get away with anything.
The 71-year-old Prime Minister leads an 87-member government against a 21-member opposition.
But the opposition has urged him to step down over his alleged involvement in the escape of wanted Australian lawyer Julian Moti from PNG to the Solomon Islands last year.
Opposition Leader Mekere Morauta said Somare's behaviour yesterday was "emotional, unbecoming, childish, that of a man who is out of control".
In parliament this week, Speaker Jeffrey Nape banned all debate on the Moti affair, prompting Opposition accusations the government was trying to stifle debate on important public issues.
However Sir Mekere says the Prime Minister has to stand down to allow police and other agencies to investigate the Moti affair and lay appropriate charges.