Christian evangelical groups in the US are attempting a "cultural colonisation" of Africa, opening offices in numerous countries to promote attacks on homosexuality and abortion, according to an investigation by a liberal thinktank.

American religious organisations are expanding their operations across the continent, lobbying for conservative policies and laws and fanning homophobia, argues the Boston-based Political Research Associates (PRA).

The groups include the American Center for Law and Justice (ACLJ), founded by the televangelist Pat Robertson, which has established bases in Kenya and Zimbabwe.

"The religious right [in effect] claims that human rights activists are neocolonialists out to destroy Africa," the report states. Groups named in it vehemently rejected the claims.

Entitled Colonising African Values: How the US Christian Right is Transforming Sexual Politics in Africa, the study analysed data from seven African countries and employed researchers for several months in Kenya, Malawi, Zambia and Zimbabwe.

It identified three organisations it believes are aggressively targeting the continent: Robertson's ACLJ, the Catholic group Human Life International and Family Watch International, led by the Mormon activist Sharon Slater.

Each of these "frame their agendas as authentically African, in an effort to brand human rights advocacy as a new colonialism bent on destroying cultural traditions and values", the report says.

In the past five years, the report alleges, all "have launched or expanded Africa-based offices dedicated to promoting their Christian right worldview. A loose network of rightwing charismatic Christians called the transformation movement joins them in fanning the flames of the culture wars over homosexuality and abortion by backing prominent African campaigners and political leaders."

Dr Kapya Kaoma, an Anglican priest from Zambia and author of the report, said rightwing Christian groups encourage perceptions that same-sex relations are "un-African" and imposed by the west, a view that is in fact based on the Bible that arrived with colonialism rather traditional African culture.