DAKAR, Senegal — Cameroon’s military has forcibly deported at least 100,000 Nigerian asylum seekers in the past two years in an effort to slow the spread of Islamic extremism, Human Rights Watch said Wednesday.

The deportations defy a request by the U.N. Refugee Agency to protect refugees and not force any returns to Nigeria until the “security and human rights situation has improved considerably,” the rights group said. Nigerians being sent back are facing more violence, destitution and further displacement, it said.

“Since early 2015, Cameroonian soldiers have tortured, assaulted, and sexually exploited Nigerian asylum seekers in remote border areas, denied them access to the UN refugee agency, and summarily deported, often violently, tens of thousands to Nigeria,” Human Rights Watch said, adding that conditions at a Nigerian refugee camp in Cameroon were poor.

The rights group’s associate refugee director Gerry Simpson called on Cameroon to protect refugees fleeing Boko Haram in northeast Nigeria.

“The Cameroonian military’s torture and abuse of Nigerian refugees and asylum seekers seems to be driven by an arbitrary decision to punish them for Boko Haram attacks in Cameroon and to discourage Nigerians from seeking asylum,” he said.

Cameroonian authorities deny forcing Nigerian asylum seekers to return or committing any abuses against them.

Cameroon contributes to a multinational force meant to stamp out the Nigeria-based extremists who have been staging attacks around the Lake Chad region.

Human Rights Watch said many of the 60 asylum seekers interviewed had said that they were accused of belonging to Boko Haram.

The United Nations High Commissioner for Refugees said it has heard similar accounts from Nigerians living along Cameroon’s border region. They described children being separated from parents and people getting inadequate food and medical care.

The rights group said that Cameroon has the right to regulate the presence of non-nationals, but that authorities must not block and deport refugees seeking asylum.