An Australian journalist and his Thai colleague were acquitted of criminal defamation Tuesday over a report implicating Thailand's navy in human trafficking, as the country faces heavy criticism for its role in the deadly trade.

The pair were also found not guilty on another charge of breaching the nation's tough Computer Crimes Act in a high-profile trial that had sparked condemnation from human rights groups and the United Nations.

Alan Morison and Chutima Sidasathian, of the Phuketwan news website, had faced up to seven years in jail over a July 2013 article quoting a Reuters news agency investigation that said some Thai navy members were involved in trafficking Rohingya Muslims fleeing Myanmar.

"The court has acquitted (the pair)," their lawyer Siriwan Vongkietpaisan told AFP shortly after the verdict was delivered at Phuket Provincial Court.

The ruling is a rare bright spot for the media in a nation governed by a junta that has stamped down on freedom of expression.

Amnesty International welcomed the verdict but added that the two journalists "should never have had to stand trial in the first place".

"This is just the latest in a long line of attacks on freedom of expression and media outlets since the military seized power in 2014," regional spokesman Josef Benedict said.

The acquittal comes after the region's people-trafficking trade was dramatically laid bare this year when dozens of migrants' graves were found on the Thai-Malaysia border.

As the network unravelled amid a Thai crackdown, migrants were abandoned at sea and in jungle camps, in a crisis that eventually forced Southeast Asian governments to respond.

- Trade in humans -

Speaking to AFP after the verdict, Chutima said: "The judge did the right thing, this is a big step for freedom of expression and freedom of the media in Thailand."

Southern Thailand has long been known as a nexus for lucrative and largely unchecked smuggling networks through which persecuted Rohingya Muslims in Buddhist-majority Myanmar, and Bangladeshi economic migrants, pass on their way to Malaysia.

Officials have been accused by human rights groups of turning both a blind eye to -- and complicity in -- the trade.

Thai prosecutors have indicted 72 people over the trade, including local officials and a senior army general.

However no other military figures have been arrested, something that has raised eyebrows among rights groups and observers who say it is unlikely such an influential officer would have acted alone.

Last month -- for the second year in a row -- Thailand was placed by the United States on the bottom tier of its ranking of countries failing to tackle human trafficking alongside nations like Iran, Libya, North Korea and Syria.

Reuters has not been charged over its reporting -- part of a series honoured with a Pulitzer Prize last year -- and rights groups had accused the navy of trying to muzzle the smaller Phuket-based English-language media outlet.

David Crundwell, a chief spokesman for Reuters, said the agency was "pleased" to hear the verdict.

The navy has 30 days to appeal against the verdict.