Dr Benjamin Carson, a neurosurgeon with Johns Hopkins University and a conservative speaker, has come under fire for comments made on Fox News comparing gay people to a pedophilia advocacy group, as well as to bestiality.

On Tuesday Dr Carson appeared on Fox News, and told the show’s host, Sean Hannity: “My thoughts are that marriage is between a man and a woman. It’s a well-established, fundamental pillar of society and no group, be they gays, be they NAMBLA (North American Man/Boy Love Association), be they people who believe in bestiality–it doesn’t matter what they are–they don’t get to change the definition.”

The remark sparked outrage due to the apparent comparison of same-sex marriage to pedophilia and bestiality.

Students at Johns Hopkins University, where Dr Carson is scheduled to give a commencement address, arranged a petition for him to be pulled from the role.

The Health and Human Rights Student Group wrote: “We retain the highest respect for Dr. Carson’s achievements and value his right to publicly voice political views. Nevertheless, we feel that these expressed values are incongruous with the values of Johns Hopkins and deeply offensive to a large proportion our student body.”

Dr Carson told MSNBC News that he would consider pulling from the commencement address: “This is [the students'] day and the last thing I would want to do is rain on their parade.”

He went on to defend himself against allegations of anti-gay speech, saying that when he referred to gay people, NAMBLA, and bestiality: “I wasn’t equating those things, I don’t think they’re equal. If you ask me for an apple and I give you an orange you would say, that’s not an orange. And I say, that’s a banana. And that’s not an apple either. Or a peach, that’s not an apple, either. It doesn’t mean that I’m equating the banana and the orange and the peach. In the same way I’m not equating those things.”

Mr Carson became popular in conservative political circles after he spoke out against Obamacare at the National Prayer Breakfast, a high-profile event attended by President Obama.

Earlier this month Mr Carson announced his retirement from neurosurgery, and suggested he may take up politics.