Penn has voiced his admiration for Chavez on numerous occasions - the actor visited the politician in 2007 when he was writing an article about the leader, and caught up with him again in 2008.
In a 2007 interview following his first trip to the South American country, Penn said: "The first thing I'm going to say is that we know more lies about him in the United States than we know truth. If you want a soundbite from me about Chavez, then I would say that, for the moment, he's much more positive for Venezuela than he is negative."
But Venezuelan native Alonso, who appeared alongside Penn in 1988's Colors, has challenged his political views in a new missive which she hopes will "set the record straight for you regarding the Chavez regime".
She writes, "Why do you validate a government that has converted Venezuela into the second most dangerous country in the world, where impunity is above 90 per cent and its people live in a constant state of stress and fear of getting killed?
"My intention isn't to convince you, but to let you know what is truly happening in this beautiful country of noble people, Venezuela. I would encourage you to investigate in depth the 'inside story' and realize for yourself the dark side behind the person you choose to idolize.
"Agreed, Chavez did win his first elections, but like Hitler, he betrayed what the country gave him: The vote of confidence."