Women are being forced to have sex in return for Ebola vaccinations in the Democratic
Republic of the Congo, it has been claimed.
Fears of exploitation by frontline workers in the fight against the deadly disease were also highlighted as the death toll from the latest outbreak in the country passed 500.
The claims surfaced just days after the DRC's health minister said a vaccination programme has prevented thousands of more deaths.
According to The Guardian, studies have revealed concerns by 'multiple respondents' that some people are asking for sexual favours in return for Ebola treatments - including vaccinations.
The matter was raised as officials gathered for a national task force meeting in the city of Beni.
They were told how research by NGOs had found there was widespread mistrust in health workers in DRC.
On Saturday, officials revealed that more than 500 people had died from the latest outbreak of Ebola in the country, but a vaccination programme had prevented thousands of more deaths.
"In total, there have been 502 deaths and 271 people cured," said a health ministry bulletin, reporting on the outbreak in the east of the country.
But Health Minister Oly Ilunga Kalenga said that, for the first time, a vaccination programme had protected 76,425 people and prevented 'thousands' of deaths.
"I believe we have prevented the spread of the epidemic in the big cities' in the region," he said.
"The teams also managed to contain its the spread of the epidemic to neighbouring countries."
"The biggest problem is the high mobility of the population," the minister added.
The outbreak started last August in the North Kivu region, which borders Uganda and Rwanda.
The Spanish wing of the aid agency Doctors Without Borders (MSF) reported on Twitter that there had been a surge in cases since January 15.
Rwanda, Uganda and South Sudan, further north, were all now on alert, it added.
The security situation in the east of the country, where armed rebels have terrorised the population for years, has made treating the disease difficult.