Myanmar on Wednesday charged three journalists for reporting on an armed ethnic group in a case that has fuelled alarm at the erosion of press freedom.
Five men, including the trio, have now been transferred to Hsipaw prison in Shan State to await their first day in court, a police officer in the station told AFP.
They were charged under section one of the draconian Unlawful Associations Act, which carries a sentence of up to three years in prison.
The legislation was widely used against journalists and activists by the former military junta, which stepped down in 2011, paving the way for the party of pro-democracy activist Aung San Suu Kyi to assume power last year.
"Five men -- three journalists and two drivers -- were charged under 17/1 of the Unlawful Association Act this afternoon," said the police officer, who asked not to be named.
"They arrived here at 12:30 pm and were later transferred to Hsipaw prison department."
They were among seven people detained by the military on Monday as they left a drugs-burning ceremony organised by the Ta'ang National Liberation Army (TNLA), one of several rebel groups fighting the state.
The journalists included reporters from The Irrawaddy and DVB, which for years challenged the former junta's iron grip on free expression with their covert reporting.
Earlier a senior aide to Suu Kyi, who herself spent almost two decades under house arrest for defying the junta, defended the charges.
"It's true that they broke the law by going to meet ethnic groups," Win Htein, also a former political prisoner, told the Central News Bureau broadcaster.
He said it was wrong for the army to initiate proceedings but insisted that "the government should take action" against the journalists.
The military said Monday the group was stopped near Phayargyi village in Shan State, not far from where TNLA fighters have been clashing with the army.
Several soldiers and four insurgents have been killed since fresh fighting erupted last week after troops discovered a training camp for the ethnic armed group, state media reported Wednesday.
The clashes come just weeks after Suu Kyi met several ethnic insurgent groups, including the TNLA, at talks aimed at ending decades of fighting in Myanmar's borderlands.
"Getting peace is more important than amending this (Unlawful Associations) Act," said Win Htein.
The detention of the journalists has drawn condemnation from activists and diplomats concerned at growing curbs on press freedom.
The Committee to Protect Journalists' Asia Program coordinator Steven Butler called the arrests an "affront to democracy in Myanmar".
It comes amid a groundswell of activism among local journalists aimed at quashing a controversial broadly-worded online defamation law which has been used to curb criticism of the government and army.
Prosecutions under the legislation have surged since the National League for Democracy came to power last year, with social media satirists, activists and journalists increasingly targeted.