Myanmar's military-backed government has released rare photographs of detained former leader Aung San Suu Kyi receiving two books and a sealed letter sent by King Charles III, in a brief meeting it said lasted about 10 minutes.

The Presidential Press and Information Bureau said Home Affairs Ministry officials delivered the package in Naypyitaw on Monday morning. It included two gardening books, The Land Gardeners: Soil to Table by Bridget Elworthy and Henrietta Courtauld and Soil: The World at Our Feet, the catalogue of an environmental exhibition in London, as well as a sealed envelope and a sealed diplomatic communication.

The two photographs show the 81-year-old Nobel Peace Prize laureate in a pale green traditional blouse and a skirt, seated across a small table from two men in white shirts in a wood-panelled room. The statement did not say where the meeting took place, what was discussed or how the books reached Myanmar.

It was the first acknowledgement that Suu Kyi, who has been held since the February 2021 coup, had received correspondence from abroad. The military government has released only a handful of images of her in more than five years and has given little information about her health or whereabouts.

Charles, who has long campaigned on environmental protection and sustainable farming, met Suu Kyi in London in 2017, when he was Prince of Wales and she was Myanmar's state counsellor.

Kim Aris, Suu Kyi's son, said he welcomed the king's gesture but warned that the military should not use it to suggest that normal conditions had returned. "We must not allow the military regime to use such selective disclosures to create an illusion of normality or gain international legitimacy," he said in a statement. "My mother's fundamental human rights continue to be violated."

Rights groups and observers have described the release of the photographs as part of an effort by coup leader Min Aung Hlaing to improve his international standing. He was installed as president this year after elections widely criticised as neither free nor fair, and has since visited several regional countries.

Suu Kyi, who won the 1991 Nobel Peace Prize for her non-violent campaign for democracy, has spent much of her life under house arrest. She is now serving multiple sentences at an undisclosed location in the capital.