SEAN PENN has quit his job as contributing reporter for the San Francisco Chronicle, after the newspaper dubbed Venezuelan president Hugo Chavez a "dictator".

The politically charged star has carried out a series of assignments for the paper - edited by Sharon Stone's ex-husband Phil Bronstein - visiting Iraq and Iran as a contributing reporter.But Penn has severed all ties with the California publication in a stinging letter to Bronstein, which has was published in Thursday's (17Jan08) edition.Penn writes, "I could only hope this great city was more clever than its increasingly lamebrain paper. Chavez was democratically elected."In the paper's attack on Oliver Stone, who, agree with him or not, has at least the balls, passion and intellectual curiosity to pursue information away from a porcelain dumping bowl and a desperate newspaper, we see another attempt to marginalise the outspoken." Penn signed the letter "former SF Chronicle contributing reporter".Bronstein has responded, writing alongside Penn's piece, "He's a great actor and a great director. People get riled up about a lot of things. Particularly in this day and age; they get to express themselves. We were more than happy to print this letter."Sean Penn's days of writing for the San Francisco Chronicle may be over: The actor now calls the publication an "increasingly lamebrain paper."Penn offered the critique in a letter published Tuesday, written in response to a tongue-in-cheek article that focused on celebrity interest in Venezuelan President Hugo Chavez. It listed a number of potential matchups between celebrities and dictators or other authoritarian figures.Penn objected to the characterization, saying Chavez is a democratically elected leader.The acclaimed actor and director called the newspaper an "increasingly lamebrain paper" after it published a tongue-in-cheek article, saying, "celebrities making asses of themselves...hanging out with the world's most notorious dictators and other authoritarian figures".The paper listed Danny Glover, Oliver Stone and Sean Penn among those celebrities, while dubbing Chavez a dictator.In a letter to the newspaper published on Thursday, Penn writes, "I could only hope this great city was more clever than its increasingly lamebrain paper. Chavez was democratically elected, and dictators don't lose constitutional referendums.