Wa Lone and Kyaw Soe Oo, nationals of Myanmar, were arrested while carrying official documents which had just been given to them by police officers.
They have maintained their innocence, saying they were set up by police.
The case has been widely seen as a test of press freedom in Myanmar.
“I have no fear,” Wa Lone said after the verdict. “I have not done anything wrong. I believe in justice, democracy and freedom.”
Chit Suu Win, wife of Reuters journalist Kyaw Soe Oo, is seen crying behind barbed wire after the verdictImage copyrightREUTERS
Kyaw Soe Oo’s wife, Chit Suu Win, broke down in tears on hearing the verdict
The two men, who both have families with young children, have been in prison since their arrest in December 2017.
What were they investigating?
Wa Lone, 32, and Kyaw Soe Oo, 28, are Myanmar citizens who were working for the international news agency.
They had been collecting evidence about the murders of 10 Rohingya men by the army in the village of Inn Din in northern Rakhine in September 2017.
They were arrested before the report’s publication, after being handed some documents by two policemen who they met at the restaurant for the first time.
A police witness testified during the trial that the restaurant meeting was a set-up to entrap the journalists.
The 10 Rohingya men before they were killed at Inn DinImage copyrightREUTERS
These are the men whose deaths the Reuters journalists were investigating
The final report – a collabortion with other colleagues – was considered extraordinary, because it gathered testimonies from a range of participants, including Buddhist villagers who confessed to killing Rohingya Muslims and torching their homes. Accounts from paramilitary police also directly implicated the military.
The military had previously released its own investigation into allegations of abuse in Rakhine, and exonerated itself of all wrongdoing.
Authorities later launched their own probe into the Inn Din killings, confirming the massacre took place and promising to take action against those who had taken part.
What is happening to the Rohingya?
At least 700,000 Rohingya have fled violence in the country in the past year.
The crisis erupted when a brutal crackdown was launched in response to a Rohingya militant group attacking several police posts.
The United Nations has called the army’s response – including murder, torture, rape, sexual slavery, persecution and enslavement – “grossly disproportionate to actual security threats”.
Media captionRohingya girls in danger: The stories of three young women
A UN report – released last week – called for military leaders to face genocide charges for their actions.
Myanmar rejected the report. It sees the Rohingya – who have their own culture and language – as illegal immigrants from Bangladesh.
What did the judge say?
Judge Ye Lwin told the court in Yangon the pair had “intended to harm the interests of the state”.
“And so they have been found guilty under the state secrets act,” he said.
The verdict had been delayed once because of the judge’s ill health.
A crushing blow to freedom’
Nick Beake, BBC Myanmar correspondent, Yangon
Wa Lone and Kyaw Soe Oo bowed their heads as the verdict was delivered, while their families broke down in tears in court.
The reporters have always insisted they were framed. Wa Lone – who missed the birth of his first child while being detained – protested his innocence once again as he was led away.
Many will see this verdict as a crushing blow to freedom of the press in Myanmar and another setback for democracy, three years after Aung San Suu Kyi’s party triumphed in free elections.
Last week, UN inspectors called for Myanmar’s top generals to stand trial for genocide for the crimes committed against the Rohingya – the very subject these reporters were investigating.
What is the reaction to the jailing?
“Today is a sad day for Myanmar, Reuters journalists Wa Lone and Kyaw Soe Oo, and press freedom anywhere,” Reuters editor-in-chief Stephen Adler said.
Read their report ‘Massacre in Myanmar’
The story behind the journalists’ arrest
Blow by blow: How a ‘genocide’ was investigated
The verdict has been widely criticised by observers and human rights groups.
Protesters with banner calling for the journalists to be freedImage copyrightREUTERS
Ahead of the verdict, people marched to show solidarity
“We are extremely disappointed by this verdict,” Britain’s ambassador to Myanmar, Dan Chugg, said according to Reuters.
US ambassador Scot Marciel echoed the same criticism, saying the court’s decision was “deeply troubling for everybody who has struggled so hard here for media freedom”.
The UN’s resident and humanitarian co-ordinator in Myanmar, Knut Ostby, said the UN had “consistently called for the release” of the journalists and that “a free press is essential for peace, justice and human rights for all. We are disappointed by today’s court decision”.
Skip Twitter post by @knutostby
A free press is essential for peace, justice and human rights for all. We are disappointed by today’s court decision. Our full statement:#Myanmar #FreeWaLoneKyawSoeOo pic.twitter.com/sxeCJYTKRd
— Knut Ostby (@knutostby) September 3, 2018
End of Twitter post by @knutostby
“The outrageous convictions show Myanmar courts’ willingness to muzzle those reporting on military atrocities,” Brad Adams, Asia director at Human Rights Watch, said.
“These sentences mark a new low for press freedom and further backsliding on rights under Aung San Suu Kyi’s government.”
Media access to Rakhine is strictly controlled by the government so it is difficult to get reliable news from the region.
What next for Myanmar after damning report?
Myanmar rejects UN ‘genocide’ accusation.
With many thanks to: BBC Europe for the original story.