A legal challenge to Australia's asylum seeker processing centre on Manus Island by the Papua New Guinea opposition leader ''smacks of politics,'' according to Labor MP Mark Dreyfus.
PNG Opposition Leader Belden Namah launched the challenge with the National Court last Friday, saying he believed the processing centre was unconstitutional and that detainees were being held illegally.
''The ministers of the O'Neill-Dion government have now received a summons to appear and defend their conduct in the National Court,'' he said in a statement.
''We will take this matter as far as necessary to ensure that the values of our nation's constitution are upheld.''
Mr Dreyfus, who is the federal cabinet secretary as well as a QC, said the Labor government had reached an agreement on regional processing with the PNG government.
''I think when you've got the opposition leader in Papua New Guinea bringing a proceeding in the Supreme Court [in] Papua New Guinea, it does smack of politics to me,'' he told Sky News on Monday.
The memorandum of understanding [MOU] between Australia and Papua New Guinea states that transfers of people to PNG's Manus Island, and the running of the centre, will be run in accordance with both countries' laws.
''The government of Australia will conduct all activities in respect of this MOU in accordance with its constitution and all relevant domestic laws [and] the government of Papua New Guinea will conduct all activities in respect of this MOU in accordance with its constitution and all relevant domestic laws,'' it states.
It is this aspect of the constitution that the PNG opposition is challenging in court.
Mr Namah said the court challenge asked the courts to declare that the MOU is unlawful because it allows Australia to force asylum seekers to enter PNG territory, and allows the PNG government to deprive those asylum seekers of their liberty as soon as they enter Papua New Guinea.
In a statement, Mr Namah said: ''Our claim, that the asylum seekers detention scheme is unconstitutional and that the detainees on Manus are held illegally in PNG, has never been legitimately addressed by the government and must now be answered in our highest courts.''
Mr Namah said the legal challenge also attempted to ''remedy the many abuses of PNG law and of ministerial powers which have given rise to the situation on Manus''.
He said the opposition challenged the right of the government to force people seeking refugee status in Australia to enter PNG, where they were being held ''illegally and indefinitely under inhumane conditions''.
''We challenge the right of the government to make this arrangement with the government of a foreign nation, again in contravention of our constitution,'' he added.
The injunction seeks to have the current detainees released and to prevent the government from receiving or detaining any more asylum seekers from Australia.
''I am confident that our justice system will succeed in upholding this truth, where our government has so regrettably failed,'' Mr Namah said.
Mr Dreyfus said he would not comment further on the challenge's chances of success under the PNG constitution.
A spokesman for Immigration Minister Chris Bowen's said: ''We have a binding MOU with the PNG government and that is working well. We are not going to comment on politics or court matters in another country.''
He said it was unclear whether Australia would be required to have a role in the court case.
The MOU between the Australian and PNG governments says that, in the event of a dispute, ''Any dispute arising with respect to the interpretation or implementation of this arrangement will be settled amicably through consultation between the participants.''
PNG's The National newspaper reported that lawyer Loani Henao had filed court proceedings at the Waigani National Court on Friday.
"The basis of that (the court proceeding) is that the asylum seekers have no interest in coming to PNG," Mr Henao told The National. "The moment they entered PNG, they were detained."
Henao told the newspaper that under section 42 of the Constitution, all persons, including foreigners, had personal liberties that were protected under PNG law.
"They never entered this country on their own accord."
Refugee and Immigration Legal Centre principal David Manne said Australian refugee lawyers would be watching the case with interest.
Acting opposition immigration spokesman Michael Keenan said, "ultimately it's a matter for PNG, but it smacks of this government not doing its homework".
Labor's 'failed border protection policies'
Coalition MP Steven Ciobo told Sky News the challenge was a consequences of Labor's ''failed border protection policies''.
''[The PNG Opposition] realise what a massive problem Australia has . . . You've got the opposition saying we have real concerns,'' Mr Ciobo said.
Mr Ciobo said while Manus Island was used by the the Coalition during Howard years ''the contrast could not be more stark''.
'Reasonable' prospect of success
Mr Namah's legal challenge has "reasonable" prospect of succeeding, according to an Australian lawyer who works in PNG.
The lawyer, who asked not to be named, told The National Times that the PNG Constitution had a very strong bill of rights. He said that some rights applied only to citizens but others - such as "liberty of the person" - applied to non-citizens, too.
While liberty could be deprived to prevent a person's unlawful entry into PNG or for extraditions and expulsions, the lawyer said that entry by asylum seekers was not unlawful if they'd arrived under an agreement with the PNG government.
The National Times understands that the Manus Island processing centre is not a "really big issue" in PNG, but there are still undercurrents of resentment towards Australia where PNG's sovereignty is perceived to be compromised.
"The Leader of the Opposition is taking [the challenge] up mainly to embarrass the [O'Neill] Government," the lawyer said.
As it is a constitutional issue, the legal challenge is expected to be referred from the National Court, which has one judge, up to the Supreme Court, where there are up to 5 judges.