Two people have been arrested as part of a fraud investigation into the sale of fire-resistant window glass in Northern Ireland.
The probe is linked to a complaint about the quality of some of the product supplied by Co Antrim company Glassworks Ireland Ltd.
Some glazing had been marked as Pyroguard by the firm - even though it had not purchased the widely-recognised product from the manufacturer, police said. A senior officer urged customers to check its legitimacy.
PSNI detective chief inspector Colin Gillis said: "It is extremely important that anyone who has had fire resistant glass supplied by this company takes steps to confirm it is the legitimate product, even if the glass is marked with an official stamp and has an accompanying certificate of authenticity implying that it is fire resistant glass."
Glassworks Ireland Ltd is based in Randalstown but the company has a diverse customer base in the construction industry across Northern Ireland and elsewhere.
Its website promised the highest level of customer service and said the 21-year-old company had become a principal supplier of glass products throughout Ireland and the UK to commercial and domestic markets.
Mr Gillis said: "Inquiries to date have given us sufficient cause to believe that in order to safeguard the public it is both appropriate and necessary to issue this advice to customers.
"There is absolutely no concern regarding Pyroguard products supplied by other companies and our appeal is only to those who have dealt with Glassworks Ireland Ltd.
"To date we have arrested and interviewed two people as part of the fraud investigation. They have since been released on bail pending further inquiries."
He urged people who had bought glass marked Pyroguard from Glass Works Ireland Ltd to contact Pyroguard manufacturer CGI to check its authenticity and if found to be substandard to call police.