WASHINGTON (Thomson Reuters Foundation) - One in five people worldwide report having paid a bribe for land, with rates even higher in sub-Saharan Africa where women say they are forced to trade sex for property rights, according to research by a top global anti-corruption watchdog.

With women increasingly involved in agriculture in Africa, their livelihoods become more vulnerable to such sexual extortion, according to a report by Transparency International presented on Wednesday to the World Bank Conference on Land and Poverty.

For such women, access to and control of land is critical to their incomes, food supplies and social welfare, it said.

Globally, one in five people reported paying a bribe for land services, the report found.

In sub-Saharan Africa, one in three people reported having done so, with women in the region reporting sexual extortion as the most pertinent land corruption issue, it said.

Sexual extortion in land transactions tends to harm women who are young, single or widowed and cannot afford to pay cash bribes, it said.

It occurs when women seek land titles or negotiate access to property, it said.

Data from Ghana last year showed nearly 40 percent of women compared with 23 percent of men said corruption hindered their access to and control over land resources, it said.

“The ways in which women are more commonly exposed to corruption is through bribery and harassment, including sexual harassment,” it said.

Women also tend to be taken advantage of due to a lack of knowledge of their rights and to low levels of literacy, the report noted.

Transparency International, based in Berlin, added that there were major challenges in gathering evidence on sexual extortion, due to cultural sensitivity and issues of psychological coercion, consensual sexual relationships and victim blaming.

Some countries reported that survey teams were stymied because they needed permission from women’s families or spouses first, and husbands often accompanied their wives during their interviews.

Sexual extortion could be prosecuted under anti-corruption laws as well as laws against gender-based violence, sexual harassment and discrimination, the report said.

However, anti-corruption laws very often lack specific reference to sexual extortion, it said.