A knifepoint robbery occurred at the A & M supermarket, Heol Gwili in Llwynhendy at approximately 4.10pm on Sunday, 3rd July 2016.
The male suspect made threats but no one was harmed and nothing was stolen before he left.
Police wish to reassure the community that this type of incident is rare and that the investigation is progressing.
A 25-year-old man from the Llwynhendy area has been arrested on suspicion of robbery. He is currently in police custody.
Any witnesses who saw the individual on a bicycle with his face covered between 3-4.30pm, or anyone who has information about this incident, is urged to call Llanelli Police immediately on 101 or anonymously call Crimestoppers on 0800 555 111.
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