Marco Pierre White has been accused of promoting cigarettes during his recent television series, Marco's Great British Feast, after appearing on screen smoking.
Ofcom is investigating whether the programme broke the rules after complaints from nine people. Its code states that programmes should not seek to glamorise cigarettes to under-18s.
In the first episode of the ITV series on 2 July, White, 46, was pictured holding or smoking a cigarette on at least eight occasions. In the second show he had three cigarettes in the first six minutes.
If ITV is found to have breached the code Ofcom could impose a fine, but the broadcaster is confident as the show was screened after the watershed.
"The sequences showing him smoking were editorially justified as reflecting his day-to-day activity," said a spokesman. White was not shown smoking during the preparation of food. His spokeswoman made no comment.