US Energy Secretary Rick Perry has attracted backlash after suggesting that fossil fuels would play a "positive role" in preventing sexual assault cases in Africa.

Energy through fossil fuels would bring light and "righteousness" and decrease crime, Perry said while addressing a forum in Washington on Thursday (2 November).

His remarks reportedly offended several pro-environment groups that demanded his immediate resignation, terming him unfit for the role.

"It was already clear that Rick Perry is unfit to lead the Department of Energy, but to suggest that fossil fuel development will decrease sexual assault is not only blatantly untrue, it is an inexcusable attempt to minimise a serious and pervasive issue," Michael Brune, the executive director of environmental group Sierra Club, said, according to American Broadcasting Corporation.

"Perry's attempt to exploit this struggle to justify further dangerous fossil fuel development is unacceptable. He does not deserve to hold office another day with these twisted ideas," Brune added.

The former Texas Governor was refuting claims by environmentalists that fossil fuels were harmful and contributed to climate change.

"Let me tell you where people are dying, is in Africa, because of the lack of energy they have there," Perry said in his speech. "It's going to take fossil fuels to push power out into those villages in Africa.

"A young girl told me to my face, one of the reasons that electricity is so important to me is not only because I'm not going to have to try to read by the light of a fire and have those fumes literally killing people, but also from the standpoint of sexual assault," Perry noted, adding, "When the lights are on, when you have light that shines, the righteousness, if you will, on those types of acts."

Clarifying his statements, the energy department later said in a tweet that the secretary "was making the important point that while many Americans take electricity for granted, there are people in other countries who are impacted by their lack of electricity".

The tweet further mentioned Perry's visit to Africa in October where he discussed oil and gas partnerships in the region. "The Secretary just returned from Africa... he was told how light can be a deterrent to sexual assault and can provide security in remote areas. Powerful stories like this stuck with him," the tweet read.