An Australian journalist facing criminal defamation charges in Thailand has decided to return to the country to fight for press freedom, despite the possibility of a seven-year jail term.

Alan Morison, editor of an online news site in Phuket and a former employee of the Melbourne Age, is set to be tried in July with Thai colleague Chutima Sidasathian over an article about the trafficking of refugees from Myanmar.

The story, published on the independent news website Phuketwan, contained excerpts from a Reuters special report alleging Thai military involvement in human trafficking of Muslim Rohingyas.

Morison managed to leave Thailand to visit his sick father, but was scheduled to return to Thailand today to fight the charges.

"[Criminal defamation] is a very serious offence in Thailand and we could be ... subjected to seven years jail under the maximum penalty," he said.

"We hope that doesn't prove to be the case because we think the case really shouldn't have been brought in the first place."

Morison said the trial also raised the important issue of press freedom, and that he and his colleague were relying on the Thai justice system "to give us a fair trial and to be exonerated".

"Thailand is my home and has been for 12 years, and I have faith in people there to make good decisions and to be able to determine right from wrong," he said.

"That's why I'm going back. I also think that the broader issue is the freedom of the media, and more than 100 journalists around the world are being persecuted in similar fashion using strong laws that probably shouldn't be used at all.

"So I think it's a very important issue to come back and defend our case."

Most of the estimated 800,000 Rohingya in Myanmar are regarded by the authorities there as illegal immigrants.

The Muslim Rohingya in the western Rakhine State have borne the brunt of religious violence that erupted in June 2012 and a growing number have sought to leave Myanmar.