A man was arrested after he was found with a lock knife in Sheffield city centre.
The 25-year-old was searched by police in the Devonshire Green area and a lock knife and stolen bank card were found.
He was arrested on suspicion of fraud and possession of a bladed article.
South Yorkshire Police said officers were in the area following up reports of anti-social behaviour.
A force spokesman said: "Officers want to remind people of the dangers of carrying knives in public, which not only carry a maximum sentence of four years' imprisonment but also can lead to more serious offences being committed.
"Anyone with information about somebody carrying a knife are encouraged to call us."
Call South Yorkshire Police on 101 or Crimestoppers on 0800 555111.