Two Reuters reporters were arrested in Myanmar on Tuesday night for illegally having "secret police documents," according to reports.

The U.S Embassy in Myanmar called their arrests “highly irregular” and said the two journalists, Wa Lone and Kyaw Soe Oo, were initially invited to meet with police officials in Yangon, the country’s largest city.

No further details of the arrests were given, but the U.S Embassy said it is urging the government to explain the arrests.

“For a democracy to succeed, journalists need to be able to do their jobs freely,” the embassy said.

The Myanmar Press Council said Wednesday the two journalists were accused of illegally having “secret police documents,” the Associated Press reported.

The two reporters were charged with violating the country’s Official Secrets Act, a law dating back to the 1920s. Violations are punishable by up to 14 years in prison.

A government spokesman confirmed the arrests to Reuters but did not explain why the reporters were arrested.

“Yes, it is correct that they were arrested,” Zaw Htay told Reuters. “Not only your reporters, but also the policemen who were involved in that case. We will take action against those policemen and also the reporters.”

Abbe Serphos, Reuters global communications chief, said the news organization is “urgently seeking more information about the circumstances of their arrest and their current situation.”