A lawyer at the centre of an investigation involving suspect payments to him by the Papua New Guinea government has been arrested by police.

Lawyer Paul Paraka was arrested in the early hours of Wednesday morning and taken to the fraud squad office in Port Moresby.

Radio Australia’s reporter Firmin Nanol says Mr Paraka was questioned over his law firm allegedly receiving payments of more than $AUS30 million from PNG’s finance department.

The allegations suggest the government was involved in engaging the law firm and making payments with no formal agreement and without going through proper channels.

Mr Paraka has been charged with a crime, but details were not immediately available.

He told reporters he will fight the charge in court and that he was simply being paid for government work.

He says the police are just doing their job but they are being used, and the matter has been politicised.

On the floor of parliament, opposition leader Beldan Namah has tabled a letter allegedly signed by Prime Minister Peter O’Neill authorising the payment.

Mr Namah says there is no agreement from the Office of the Attorney-General which gives legal advice to the government on any government contract or legal matter.

Prime Minister O’Neill told the media this week that the government will not stop, suppress or intimidate the work of the anti-corruption Investigation Task Force Sweep and the police.

He claims any signature on paperwork tabled by Mr Namah is a forgery.