YANGON (Reuters) - A Myanmar judge on Tuesday allowed the submission of evidence police say they obtained from the mobile phones of two Reuters reporters arrested in December for alleged possession of secret documents, in what has become a landmark press freedom case.

Detained Reuters journalist Wa Lone speaks to the media, while escorted by police, after a court hearing in Yangon, Myanmar May 22, 2018. REUTERS/Ann Wang

The court in Yangon has been holding hearings since January to decide whether Wa Lone, 32, and his Reuters colleague Kyaw Soe Oo, 28, will be charged under the colonial-era Official Secrets Act, which carries a maximum penalty of 14 years in prison.

After two days of legal argument, Judge Ye Lwin ruled he would accept as evidence printed copies of documents that a police witness said were found on their phones. The documents included alleged confidential government letters and plans for the development of an island off Myanmar’s west coast for tourism.

(Follow latest updates on detained reporters here)

So far the case has focused on documents police say the reporters were holding in their hands when they were arrested on Dec. 12, and the prosecution did not explain how the latest documents related to the case against the two journalists.

“Most of the documents are about a project plan for Rakhine State development and information about drugs seizures in the Maungdaw area. It seems like even Rakhine State development plan is a secret,” said Kyaw Soe Oo after the hearing.

Prosecutor Kyaw Min Aung declined to comment.

Defense lawyer Than Zaw Aung had argued the documents should not be admitted as evidence, saying it was unclear who has had access to the phones and whether appropriate procedures were followed during the extraction of the files.

He said some of the documents had been taken from the Facebook messenger app and that the prosecution had not shown the reporters themselves had even downloaded them.

“For some of the documents, they didn’t even know that they received those documents into their phones. During the hearing, several messages were received when the phone was turned on,” Than Zaw Aung told reporters after Tuesday’s proceedings.

“It’s a worrisome situation because anything could have happened when the accused were arrested and they no longer possessed their phones.”

The prosecution said the files were extracted “systematically” by a police IT expert, Major Aung Kyaw San.

Myanmar government spokesman Zaw Htay was not immediately available for comment after Tuesday’s hearing. Previously, he has said Myanmar courts were independent and the case would be conducted according to the law.

The next hearings in the case are scheduled for Monday and Tuesday next week.

At the time of their arrest, the reporters had been working on an investigation into the killing of 10 Rohingya Muslim men and boys in a village in western Myanmar’s Rakhine state. The killings took place during an army crackdown that United Nations agencies say sent nearly 700,000 people fleeing to Bangladesh.

The reporters have told relatives they were arrested almost immediately after being handed some rolled up papers at a restaurant in northern Yangon by two policemen they had not met before, having been invited to meet the officers for dinner.

Last month, Police Captain Moe Yan Naing testified that a senior officer had ordered his subordinates to plant secret documents on Wa Lone to “trap” the reporter.

At a news conference on May 15, Police Director General Aung Win Oo dismissed the testimony as untruthful.

After his court appearance, Moe Yan Naing was sentenced to a year in jail for violating police discipline and his family was evicted from police housing. Police have said the eviction and his sentencing were not related to his testimony.

Global advocates for press freedom, human rights activists, as well the United Nations and several Western countries, have called for the release of the Reuters journalists.