Dyfed Powys Police say the couple were seen taking part in “sexual activity” on grass near Granby Close in Llanelli, off Embankment Road.
A 40-year-old man has been arrested in connection with the incident, but police are appealing for help in locating his female partner.
A spokesperson for Dyfed Powys Police said: “Dyfed-Powys Police is investigating a report of outraging public decency that occurred in Llanelli, at approximately 4.45pm on Saturday, May 10, 2025.
“The incident involved a male and female who were reportedly taking part in sexual activity on the grass within Granby Close.
“A 40-year-old man has been arrested, however officers are now appealing to identify the woman.
“Anyone who witnessed this, or who has information about those involved, is asked to report it to us.”
