Sports Direct has apologised for issuing a notice that appeared to ban staff from speaking languages other than English in its Bangor store, saying it was a "misunderstanding".
It was understood to have been posted on a wall telling staff to only speak English for health and safety reasons.
A statement issued by the company said it had sent the guidance on its language policy to all UK stores.
Welsh Language Commissioner Meri Huws is investigating any breaches in rules.
The notice, which was printed on Sports Direct-headed paper, was criticised by Plaid Cymru AM Sian Gwenllian who said it was "discriminatory" in an area where a lot of people speak Welsh.
In a statement, the firm said the notice was intended to ensure that all staff fully understood health and safety briefings, and that the note would be re-written and re-issued.
"English is the most common language used by our multi lingual staff and, therefore, the most likely to be understood by all," it said.
"This notice was not intended to restrict the use of the Welsh language, or prohibit staff from communicating in their local language, outside these briefings or with customers.
"We will be reviewing the wording of the notice to ensure this is made clearer and re-issuing an updated notice. We are an international business and fully support the use of the local language in all our jurisdictions."
It added: "We apologise for any misunderstanding or upset this notice has caused."