Paris, May 19 (IANS): A cartoonist who designed the cover image of the French satirical weekly Charlie Hebdo, said he is leaving the publication, media reported on Tuesday.

The magazine's office in Paris was attacked on January 7. The two Islamaist attackers -- Cherif and Said Kouachi -- killed at least 12 people, including its chief editor.

Cartoonist Renald Luzier, fondly known as Luz, told the French newspaper Liberation on Monday that his job had become "too much to bear" following the deaths of his colleagues, BBC reported.

Within days of the attack, the satirical magazine's surviving staff produced an edition with the headline "All is forgiven" above Luz's cartoon of Muhammad holding a sign saying "Je suis Charlie".

"Each issue is torture because the others are gone," Luz said.

He joined the publication in 1992 and said his resignation was "a very personal choice". He will leave in September.

"Spending sleepless nights summoning the dead, wondering what Charb, Cabu, Honore, Tignous would have done is exhausting," he added.

Last month, Luz announced he would stop drawing images of the Prophet, as it no longer interested him.