To date, 50 counterfeit bottles have been found on sale in 11 shops in Hackney and Lambeth.
Effects of methanol poisoning include severe abdominal pain, the risk of coma and blindness.
Johnnie Walker distributor Diageo said there was no reason to believe the counterfeit whisky had been sold elsewhere in the country and that retailers who have bought the product directly from Diageo should not be concerned.
Diageo is working with Trading Standards to track the source. It has advertised in the local media and trade press and has set up a retailer and consumer helpline.