BANGKOK—Police in Thailand and Australia arrested six people on Tuesday as part of a yearlong, multination operation against human trafficking networks.

Thai police said they arrested an Iraqi man and a Thai woman in Bangkok, while Australian police arrested four men in Sydney and Melbourne.

Thai police Lt-Gen Wiboon Bangthamai said the arrests were part of “Operation Arapaima,” a year-long effort to crack down on human trafficking networks in Thailand, Malaysia, Indonesia and Australia, the smuggling destination.

Although participating in the police operation, no arrests were made in Malaysia or Indonesia. Australian police said the operation was continuing.

Australia has long attracted asylum-seekers hoping to start a new life, with thousands arriving by boat in recent years. Most are from war-ravaged nations such as Afghanistan, Sri Lanka, Iran or Iraq, and use Malaysia or Indonesia as a starting point for a sea journey to Australia.

In Thailand, the Iraqi man, Raihan Ashour Oraibi Alfatlawi, 39, and the Thai woman, Sunida Sokul, 36, were arrested on charges of passport forgery, Wiboon said.

A police raid on a house owned by Sunida found 16 fake passports for United Arab Emirates, Iraq and Iran, along with equipment to produce them, he said. Each of the suspects could get up to 10 years in jail if convicted.

According to Thai police, such fake passports cost US $400 each. They said the users travel to Thailand on either Iranian or Iraqi passports, where they obtain passports for the United Arab Emirates. Because the UAE enjoys peace and a higher standard of living, its passport-holders are less likely to be suspected of seeking residence abroad.

A statement from the Australian Federal Police said the suspects arrested there face a maximum penalty of 20 years in prison on two people smuggling charges.

The statement alleged that the “Australian-based targets of this operation were key organizers and facilitators of a people smuggling syndicate responsible for planning and facilitating the unlawful arrival of numerous people to Australia.”

“The organizers of these ventures are taking advantage of vulnerable people and are putting their lives at risk,” it said.