Speaking to BBC radio from Lebanon on Monday, where he now lives, Bakri claimed "everybody" now acknowledged that cartoons of the prophet which first appeared in a Danish newspaper in September were insulting.
"In Islam, God said, and the messenger Muhammad said, whoever insults a prophet, he must be punished and executed," he added.
"This man (the cartoonist) should be put on trial and ... executed" if proven guilty.
In an apparent reference to Denmark, where the government has defended the cartoons on freedom-of-speech grounds, Bakri also said that if nations fail to put people on trial for insulting Muhammad, they must "face the consequences".
The global furore over the cartoons - reprinted in several mainly European newspapers - escalated over the weekend, with mobs attacking the Danish embassies in Damascus and Beirut.
One of the cartoons depicted Muhammad wearing a turban with a bomb hidden inside. Muslims consider images of the prophet to be blasphemous.
Syrian-born Bakri, founder of the now-dissolved Islamist group Al-Muhajiroun, was banned from Britain in August last year after earning villian status in the tabloid press for his extremist views.
Syrian-born Bakri was banned
from Britain in August last year
On Monday he tempered his remarks by saying that Muslims must not kill anyone who insulted the founder of their faith "by their own personal, individual initiative".
"We are not saying ourselves to go there and start to look to him and kill him, we are not talking about that. We are talking about Islamic rules. If anybody insults the prophet, he will have to take a punishment," he said.