A series of raids on Save the Children offices to find journalists’ sources at the Nauru detention centre were sparked after the Nauruan manager of the facility made a complaint to police.

On Thursday search warrants were executed at the offices of Save the Children for a second time in two weeks, and phones, laptops and other devices were seized.

The searches were undertaken after the Nauru government was angered by a report in Guardian Australia in which an email from the operations manager at the centre, Berilyn Jeremiah, was published. Save the Children said there was no evidence the leaked email had come from any of their staff.

Jeremiah told Guardian Australia on Thursday she made a complaint to the Nauruan police following the publication of her email.

“Leaking information through the media is breaching our law,” she said. “The service providers who have leaked this information to the media are in breach of the Nauruan cyber law.”

It is understood the Nauruan police have not disclosed to Save the Children the legal basis for the execution of the search warrants, and it has not been made clear what offence is believed to have been committed.

Jeremiah said: “You look it up. It’s in the cyber law act.

“You have a look in the cyber law and see which clause they have breached.”

The Nauruan Cyber Crime Act, passed in May, created new offences relating to child pornography and to “illegal access” of computers or program data.

But the offence applies only to information relating to national security, the enforcement of a criminal law, provision of services relating to public infrastructure and the protection of public safety.

The new legislation permits searches and seizure where there are reasonable grounds to believe an offence has been committed, which must be authorised by a judge, magistrate or registrar.

Asked whether she had made the complaint at the request of any third party, Jeremiah said: “No one asked me to do it. I did it on my own. Who would ask me to do it?”

She said she did not believe Guardian Australia had committed an offence by publishing the emails.

A spokeswoman for Save the Children said the handover for their services, which are due to expire in October, had been made more difficult by the seizure of the devices.

The spokeswoman said: “A second search warrant was executed by the Nauru police force this morning on a Save the Children office in Nauru, involving the seizure of some computers.

“Save the Children has conducted a full internal audit that found there was no evidence the leaked email, which is understood to be the target of the warrants, came from our staff. Save the Children has utmost confidence that our staff have acted at all times with great integrity, compassion and professionalism in their work supporting vulnerable children and families.

“We continue to fully cooperate with Nauru police on this matter, and our priority remains working to mitigate the harmful impacts of offshore immigration detention, to the extent that the circumstances allow.

“We continue to provide around the clock support to children and their families whose care has been entrusted to us, and remain focused on ensuring their care is transitioned smoothly to new service providers when our contract expires at the end of October. This is of course made harder by these kinds of disruptions.”

Australian Greens senator Sarah Hanson-Young condemned the police raids.

“These ongoing raids on Nauru show that the Pacific nation’s legal and judicial systems are collapsing,” Hanson-Young said.

“The situation on Nauru is spinning out of control more and more as each day passes.

“How long will the Australian government put up with employees it has contracted and sent to the island being treated in such an outrageous way?

“It’s clear that the Nauruan authorities’ first priority is cracking down on whistle-blowers not protecting the women and children who have been dumped there from assault.”