An Australian nun who spent 24 hours detained in a "cage jammed full of people" in the Philippines has been released but will face further investigation.
Sister Patricia Cox's lawyer says an order was made for her release on Tuesday afternoon, a day after the nun was taken from her house to the immigration bureau in Manila and detained for "illegal political activities".
Jobert Ilarde Pahilga told AAP the 71-year-old was released and would not be deported. But the lawyer said the case hadn't been dismissed and Sr Cox would be investigated further.
"She has done nothing wrong or illegal that would warrant her arrest, detention and possible deportation," Mr Pahilga told AAP on Tuesday.
The lawyer said his client was arrested because the National Intelligence Coordinating Agency complained she was an "undesirable alien" after joining a rally against the government in Tagum City.
But Mr Pahilga said the nun didn't join the rally and was visiting farmers and indigenous people in the area as part of her missionary work.
"Sis Pat is not an undesirable alien because her work here in the Philippines is much desired by farmers and indigenous people," Mr Pahilga said.
"The complaint by the military through the NICA should be dismissed and Sis Pat should be allowed to do her missionary works here."
Filipino Senator Nancy Binay slammed the arrest claiming it was an "excessive use of authority" and an overreaction.
"How can an Australian religious person be as outlawed as those Chinese syndicates in the country involved in drugs, gambling and prostitution?" Senator Binay said in a statement on Tuesday.
"Being a Christian nation we welcome foreign observers and religious missionaries to stay in the country as long as they complied with existing laws."
International Coalition for Human Rights chair Peter Murphy says he's shocked Rodrigo Duterte's government arrested the "gentle soul" who has lived in the Philippines for more than 27 years.
The nun, who grew up in Melbourne and attended Our Lady of Sion College, is well regarded by many people in the Philippines, he added.
"It's pretty outstanding they have decided to hit her with a sledgehammer," Mr Murphy, speaking in Sydney, told AAP on Tuesday.
"She's a very gentle soul ... a really quiet and unassuming character."
Mr Murphy, who has known Sr Fox for years and travelled with her in the Philippines, described the detention centre where she was held as "a cage jammed full of people."
Sr Fox's detention came a day after Giacomo Filibeck, a Socialist Party official from the European Union who had criticised Mr Duterte's brutal anti-drugs crackdown, was deported.
"Pat is a small fry in comparison," Mr Murphy said.
"She's not a prominent person in terms of public denunciations of the government."
Australia's foreign affairs department said it was providing consular assistance.