A group of 25 asylum seekers on Manus Island is mounting a fresh challenge in Papua New Guinea's Supreme Court against their detention.

The asylum seekers will argue that their ongoing detention breaches the right to liberty and the right to access legal representation guaranteed in PNG's constitution.

"The ultimate relief that we're seeking ... is [the] release of all detainees that are held at the [detention centre on] Lombrum navy base," said lawyer Ben Lomai, who is representing the asylum seekers.

The asylum seekers involved are from Iran, Myanmar, Pakistan, Syria and Lebanon.

The asylum seekers made contact with Mr Lomai through an intermediary while they were being detained without charge at the Manus Island provincial prison, accused of stoking protests at the detention centre in January.

The ABC has obtained copies of the court documents, including a consent form signed by the asylum seekers and emails requesting legal representation.

"I was in Indonesia detention for 18 months and was recognised as a refugee by the UNHCR," wrote one asylum seeker from Myanmar.

"Now I am being held in Manus Island (PNG) without getting any right information about our future."

PNG attorney-general Ano Pala told the ABC he had not read the documents yet, and chief migration officer Mataio Rabura was not immediately available for comment.

Lawyers for the asylum seekers this week filed a notice of motion requesting access to the detainees at the detention centre and refugees at the East Lorengau transit facility, so they can obtain official statements.

On March 18 PNG's Supreme Court is expected to decide whether to allow the lawyers into the facilities.

If access is granted, Mr Lomai plans on sending a team of up to six lawyers to record statements from the existing 25 clients and possibly other asylum seekers.

Amended constitution not retrospective, lawyer says

Mr Lomai will argue that the asylum seekers' detention on Manus Island breached Section 42 (1) and 42 (2) of the PNG constitution.

Section 42 (1) guarantees the right to liberty unless a person is suspected of committing a crime or illegally enters PNG.

Mr Lomai said the men were transferred to Manus Island under the terms of a Memorandum of Understanding (MoU) with Australia and therefore were not covered by PNG's constitutional exceptions.

However, the PNG parliament amended the constitution in early 2014 to effectively exempt the asylum seekers from the protections of Section 42.

The amended constitution now reads:

"No person shall be deprived of his personal liberty except ... for the purposes of holding a foreign national under arrangements made by PNG with another country or an international organisation that the Minister responsible for immigration matters, in his absolute discretion, approves."

"We will argue that the amendment can't be used retrospectively," Mr Lomai said.

The other part of the new case relates to Section 42 (2) of the constitution, which sets out the "five rights" guaranteed to anyone in detention in Papua New Guinea.

The asylum seekers will argue that they have not been granted access to a lawyer of their choosing.

They will also claim compensation for the long period of detention and alleged breaches of rights.

Asylum seekers also undertaking class action in Australian Supreme Court

This new challenge is slightly different to other cases underway.

While he was opposition leader of PNG, Belden Namah challenged the MoU with Australia, saying it breached Papua New Guinea's constitution.

Mr Namah was given standing to pursue the case more than a year ago, but his lawyers were not available to comment on the case's progress.

Separately, asylum seekers are undertaking a class action in the Australian Supreme Court, suing the Commonwealth for negligence relating to the standard of care provided at the detention centre and for psychological injury caused by conditions.

As of February 28, there were 1,004 asylum seekers detained at the Australian-run detention centre on Manus Island, and at least nine refugees living at the East Lorengau transit facility awaiting resettlement in PNG.