Two Reuters journalists jailed in Myanmar after they were convicted of breaking the Official Secrets Act walked free from a prison on the outskirts of Yangon on Tuesday after spending more than 500 days behind bars.

The two reporters, Wa Lone, 33, and Kyaw Soe Oo, 29, had been convicted in September and sentenced to seven years in jail, in a case that raised questions about Myanmar's progress toward democracy and sparked an outcry from diplomats and human rights advocates.

President Win Myint has pardoned thousands of other prisoners in mass amnesties since last month. It is customary in Myanmar for authorities to free prisoners across the country around the time of the traditional New Year, which began on April 17.

Reuters has said the two men did not commit any crime and had called for their release.

Swamped by media and well-wishers as they walked through the gates of Insein Prison, a grinning Wa Lone gave a thumbs up and said he was grateful for the international efforts to secure their freedom.

"I'm really happy and excited to see my family and my colleagues. I can't wait to go to my newsroom," he said. Kyaw Soe Oo smiled and waved to reporters.

Before their arrest in December 2017, the two had been working on an investigation into the killing of 10 Rohingya Muslim men and boys by security forces and Buddhist civilians in western Myanmar's Rakhine State during an army crackdown that began in August 2017.

The operation sent more than 730,000 Rohingya fleeing to Bangladesh, according to UN estimates.

The report the two men authored, featuring testimony from perpetrators, witnesses and families of the victims, was awarded the Pulitzer Prize for international reporting in May, adding to a number of accolades received by the pair for their journalism. Calls to a spokesman for the Myanmar government were not immediately answered.

Reuters Editor-in-Chief Stephen J. Adler said he was thrilled with the news.

"We are enormously pleased that Myanmar has released our courageous reporters, Wa Lone and Kyaw Soe Oo. Since their arrests 511 days ago, they have become symbols of the importance of press freedom around the world. We welcome their return," Adler said.

'Months of dialogue'

Myanmar's Supreme Court had rejected the journalists' final appeal in April. They had petitioned the country's top court, citing evidence of a police set-up and lack of proof of a crime, after the Yangon High Court dismissed an earlier appeal in January.

The reporters' wives wrote a letter to the government in April pleading for a pardon, not, they said, because their husbands had done anything wrong, but because it would allow them to be released from prison and reunited with their families.

The Reuters journalists were released at the prison to Lord Ara Darzi, a British surgeon and health care expert who has served as a member of an advisory group to Myanmars government on reforms in Rakhine State, and a Reuters representative.

"This outcome shows that dialogue works, even in the most difficult of circumstances," Darzi said.

In a statement, Darzi said discussions about the pardon for Wa Lone and Kyaw Soe Oo had involved the Myanmar government, Reuters, the United Nations and representatives of other governments but did not provide more details.

Darzi had informed Reuters this year of his efforts to secure the release of the two and the company was grateful for his role in making it happen, a Reuters spokesman said.

Darzi has been a member of an advisory commission that was formed to see through the advice from a panel headed by former UN chief Kofi Annan on solving the long-running conflict in Myanmars western region in the state of Rakhine.

Rakhine State, on the Bay of Bengal, was the home to most Rohingya Muslims in Myanmar. Hundreds of thousands fled to Bangladesh after a military-led crackdown on the region in 2017.