(CNN) -- Sweden's prime minister wants two Swedish journalists who were found guilty Wednesday of supporting terrorism in Ethiopia to be freed and returned home as soon as possible, saying they were on a "journalistic mission."
The pair could face more than 18 years in prison. Their next court appearance is scheduled for December 27 and sentencing could occur then.
Ethiopian troops captured Johan Persson and Martin Schibbye in July during an exchange of gunfire with a rebel group in the Ogaden, a prohibited region along the nation's border with Somalia, according to state media.
Ethiopians officials have accused the journalists of being accomplices to terrorism after the government declared the Ogaden National Liberation Front a terrorist group in June.
"Our starting point is and remains that they have been in the country on a journalistic mission," Swedish Prime Minister Frederick Reinfeldt said in a statement. "They should be freed as soon as possible and be able to rejoin their families in Sweden."
Reinfeldt said his government was examining the guilty verdict in consultation with the journalists and their families.
"But we are already making high-level contact with the Ethiopian government in this matter," the statement said.
But presiding judge Shemsu Sirgaga said the two "have not been able to prove that they did not support terrorism."
"They have shown that they are esteemed journalists, but we cannot conclude that someone with a good reputation does not engage in criminal acts," Sirgaga said.
Press freedom groups say the two were embedded with the rebels while working on a story about the region.
Journalists and aid workers are prohibited from entering the Ogaden, which human rights organizations say is rampant with human rights abuses against ethnic Somalis by rebels and Ethiopian troops.
"The Ethiopian army's answer to the rebels has been to viciously attack civilians in the Ogaden," said Georgette Ganon of Human Rights Watch. "These widespread and systematic atrocities amount to crimes against humanity."
Persson and Schibbye were convicted on two counts: entering the country illegally and providing assistance to a terrorist organization, according to the Committee to Protect Journalists (CPJ).
Prosecutors are recommending 13 years for the terrorism charges and an additional five-and-a-half years for entering the country illegally.
Both journalists pleaded guilty to entering the country illegally through Somalia without accreditation, according to the CPJ, which says Ethiopian officials deny media access without government minders.
"We have documented violations of due process and the politicization of their trial," the CPJ said, complaining that the government pronounced the two guilty even before the trial started.
Amnesty International also called for their release.
"There is nothing to suggest that the two men entered Ethiopia with any intention other than conducting their legitimate work as journalists. The government chooses to interpret meeting with a terrorist organization as support of that group and therefore a terrorist act," said Claire Beston with the human rights group.
Both Persson and Schibbye are contributors to the Sweden-based photojournalism agency Kontinent.
"This was the worst thing that could happen. We were hoping for a trial," the agency told CNN on Wednesday.
In a statement issued in September, Kontinent said that its journalists do not take sides or participate in any conflict and report under international rights regarding freedom of the press, which it believes should be upheld by any government.
The trial against the journalists turned into a fight for press freedom in Ethiopia, according to international journalists' organizations. In a letter sent to the United Nations, Reporters without Borders accused Ethiopia of desecrating its anti-terrorism law to lessen press freedom and penalize free speech.
"In the name of the fight against terrorism, the government muzzles dissident and critical voices, thus abusing human rights and fundamental freedoms," wrote the secretary general of Reporters without Borders, Jean-Francois Julliard.
On Wednesday, the group expressed outrage.
"This verdict is absurd and demonstrates the stubbornness of the Ethiopian authorities," Julliard said. "Instead of proving their guilt, the judge accuses them of failing to prove their innocence."
Tuesday the government freed three Ethiopian journalists who had been in custody for several days after criticizing the government, according to the Committee to Protect Journalists.
The number of journalists imprisoned worldwide has increased by more than 20 percent to its highest level since the mid 1990s according to an annual report by the organization.
CNN's Sarah Jones contributed to this report.