A Christian organisation is urging Myanmar to release the former UK ambassador, Vicky Bowman and her husband.
Bowman served as the UK ambassador to Myanmar from 2002 to 2006, and now runs the Myanmar Centre for Responsible Business.
She was arrested alongside her husband, Htein Lin, on 24 August for allegedly breaking visa rules. Her husband, an artist and former political prisoner, has been accused of helping her.
They are being held in Insein prison in Yangon and will stand trial on 6 September.
If found guilty, they face up to five years in prison.
Benedict Rogers, senior analyst for East Asia at Christian Solidarity Worldwide (CSW), said they had "clearly been targeted as part of the Myanmar army's pervasive ongoing crackdown on anyone it perceives as a threat or a critic of the regime".
Over the last 18 months, the Myanmar military have led a brutal crackdown on dissidents, political leaders, pro-democracy activists and other opponents.
Rogers called for the "immediate and unconditional release" of Bowman and Lin.
"The fact that they can treat a former ambassador in this manner is no doubt an indicator of their egregious treatment of lesser-known activists and ordinary citizens of Myanmar," he said.
"The international community must not turn a blind eye to this; the need for extensive and co-ordinated sanctions remains clear, as is the need for a sweeping global arms embargo against the Myanmar military and its enterprises."