The Commonwealth bloc of nations Friday called on Papua New Guinea to respect the rule of law and the judiciary's independence after its chief justice was charged with sedition.
Commonwealth Secretary-General Kamalesh Sharma urged restraint in a country embroiled in a messy political deadlock where both Prime Minister Peter O'Neill and former prime minister Sir Michael Somare have declared themselves the rightful leader.
On Monday the Supreme Court ruled for the second time that O'Neill's rise to power while Somare was recovering from illness was illegal and that Somare should be reinstated.
O'Neill claimed the judiciary was biased and rejected the decision, leading Deputy Prime Minister Belden Namah and 10 police to storm the court Thursday and arrest Chief Justice Sir Salamo Injia.
Papua New Guinea police confirmed Injia had been charged with sedition and would face court later Friday, prompting the Commonwealth to call for calm.
"The rule of law, the independence and impartiality of the judiciary, and constitutional, democratic governance are core Commonwealth values, which must be preserved in Papua New Guinea," Sharma said in a statement.
Australian Foreign Minister Bob Carr said the situation risked damaging Papua New Guinea's international reputation as it stands on the cusp of a massive resources boom.
"It's not good for the image that Papua New Guinea sends to the world, to its diplomatic partners or to its investors, to see action of this type," Carr told ABC radio.
"Action around the chief justice should cease and all sides should act with restraint."
The deadlock between O'Neill and Somare started last year when Somare, PNG's first leader after independence, fell ill and his family announced in June he had resigned from the post.
But he recovered and returned to challenge O'Neill who had been elected by lawmakers to the top job in August, winning the support of judges who said Somare should be reinstated.
In December 2011 the Supreme Court ruled that O'Neill should be removed in favour of Somare -- a ruling that was repeated on Monday after the panel was asked again to rule on the question due to uncertainty over the original decision.
Papua New Guinea, a poor but resource-rich country, goes to the polls on June 23 for elections in which O'Neill will attempt to cement his hold on power.
Impoverished PNG has been struggling to throw off its reputation as a politically dysfunctional and often lawless nation, and has a huge liquefied natural gas project, led by US-based corporation ExxonMobil, under way.
Papua New Guinea is one of the 54 Commonwealth states, composed mainly of former British colonies.