'We can see Brecon glowing in the sky' from streetlights
Streetlights placed at a dark sky reserve where people travel to view the Milky Way and major constellations have left a campaign group concerned.
The Brecon Beacons National Park had the night sky above it protected to prevent light pollution in 2013.
LED Street lighting was installed in Cwmdu, Powys, by the Welsh Government for "driver and community safety".
But the International Dark Sky Association - which awards the dark sky status - said this was not consistent with the ideals of dark sky preservation.
Paul Hill, organiser of Astro Camp, said Brecon was "glowing" as a result of the streetlights.