The Australian prime minister, Scott Morrison, has cast doubt on a possible plot to target Anzac Day commemorations at Gallipoli despite the arrest of a man with suspected links to Islamic State by Turkish police.

The suspect, a Syrian national, was arrested after a police operation in Osmaniye and was among several Isis members detained.

Turkish police allege the suspect, named in the charge sheet as 25-year-old Abdul Karim Helif, was planning the attack as retaliation for the mass shooting in March at mosques in Christchurch, New Zealand.

Two sim cards, one in a Samsung phone, are central to the case against him.

Morrison has confirmed the Gallipoli memorial service on Thursday will go ahead as planned. He has spoken to Australia’s chief of defence force, Angus Campbell, on the phone, who is on the ground and will address the ceremony.

“The reports that we are receiving are inconclusive about any link between that arrest and any possible planned event at Gallipoli itself,” Morrison told reporters in Townsville on Thursday. “In fact to make that assumption would be, I think, making a very big assumption.”

He noted the arrest had taken place three hours away from where the Gallipoli memorial service is held.

“It is fairly routine for Turkish authorities to arrest people with suspected terrorist links,” Morrison said.

Asked if security had been beefed up, Morrison said normal arrangements were in place.

Turkish police assessed the threat to be serious but gave no details about the nature of the proposed attack.

Australians and New Zealanders travel to Turkey each year for memorial services commemorating the failed 1915 military campaign by Anzac (Australian and New Zealand Army Corps) and allied forces to drive Ottoman troops from Gallipoli and the Dardanelles region.

Soldiers from New Zealand, Australia, Turkey and other countries held services on the peninsula on Wednesday. At dawn on Thursday, Australians and New Zealanders were due to hold a special dawn service marking the landings.

The commemorations come a month after the Turkish president, Recep Tayyip Erdoğan, faced criticism from Australia and New Zealand for comments he made after the Christchurch shooting that invoked Gallipoli.

Turkey has said Isis was responsible for bombings in 2015 and 2016 in which 200 people died. Although the militant group has not been active recently in the country, authorities still carry out routine operations against suspected Isis members.

The Australian veterans affairs minister, Darren Chester, said the arrest was primarily a matter for Turkish authorities.

“We work closely with the local Turkish authorities on security arrangements,” he told ABC Radio National on Thursday. “Obviously the tragic events in Christchurch had nothing to do with the events of 1915 on the peninsula and there’s a great deal of respect between the Turkish people and Australian and New Zealanders.”

The Australian War Memorial director, Brendan Nelson, praised Turkish authorities for dealing with the issue.

“The Turkish authorities went to extraordinary lengths to see that the Gallipoli peninsula was secure for the Anzac Day services that are being held there.”

Turkish nationals were banned from attending the dawn service amid heightened security fears.

“Unfortunately we live in a world where there are people – wherever they live, whatever their background, whatever their beliefs – who are fundamentalists intent on disrupting what we do,” Nelson said. “The most important thing we can do is go about living our lives.”

Reuters contributed to this report