Firefighters were called to a pizzeria in Kilburn after the alarm was raised over plumes of smoke seen pouring from the chimney.
Three crews attended Wood Oven Pizza in Kilburn High Road on Saturday (July 23) morning to investigate after being called by a member of the public.
A London Fire Brigade spokesperson said: "Chimney smoke could have been dangerous, so we came to check why it was smoking so much"
"There was no fire but the chimney smoke was clogged, so we had to come and check."
A worker at the restaurant said neither staff nor customers were not aware of an issue until firefighters arrived.
He told getwestlondon there was a small amount of smoke from the pizza oven but this was normal.
He said firefighters had advised staff to clean the chimney but this this already happened monthly and a cleaner was next due on Monday (July 25).
A woman died earlier this month following a blaze at an apartment block in Kilburn.
