The South African Human Rights Commission (SAHRC) on Tuesday condemned what it described as the "cold-blooded murder" of environmental activist Fikile Ntshangase in October.

Ntshangase, a vocal opponent of one of South Africa's largest open coal mines in the coastal province of KwaZulu-Natal, was involved in legal proceedings against the expansion of the venture at the time of her death, the SAHRC said.

"The (SAHRC) is deeply shocked and strongly condemns the cold-blooded murder of environmental human rights defender Fikile Ntshangase," it said, adding no arrests had been made in relation to her death.

It said human rights activists, especially in mining communities, often put their lives at risk and that it saw the killing of Ntshangase as a threat to the creation of a safe environment for activists to exercise their rights.

It called on the government to create this environment via steps including a thorough investigation into Ntshangase's death, greater enforcement of existing mining legislation and by acting on allegations of threats made against activists.

A number of other campaign groups had already raised concerns around Ntshangase's death in a joint statement signed by organisations including South Africa's Centre of Environmental Rights, local Friends of the Earth affiliate Groundwork and the Global Environment Trust.

Ntshangase was gunned down at the home she shared with her 11-year-old grandson on Oct 22, the joint statement said.

She was vice-chairperson of a sub-committee of the Mfolozi Community Environmental Justice Organisation, which had been challenging the expansion of the coal mine.

Shortly before her death Ntshangase had broken away from some of her colleagues on the committee by refusing to sign an agreement with the company operating the mine, which had already caused "untold destruction" to the environment, homes and livelihoods in the area, the joint statement said.