KAMPALA, Uganda — A repatriation program for hundreds of thousands of Somali refugees in the world’s largest refugee camp is marked by fear and intimidation by Kenyan authorities, Human Rights Watch says.

Kenya wants more than 260,000 Somali refugees to return home amid concerns that some in the Dadaab refugee camp are used by Somalia-based al-Shabab Islamic extremists to launch attacks inside Kenya.

Kenya plans to close Dadaab before the end of this year. Human Rights Watch argues that the government’s efforts to repatriate the Somali refugees don’t meet international standards for voluntary return.

“There is no way these returns can be considered voluntary,” said Bill Frelick, the group’s refugee rights director.

The statement comes as President Barack Obama plans to host a summit on refugee issues with world leaders next week during the U.N. General Assembly gathering in New York. The General Assembly also will host a summit on refugees and migrants.

Refugees now spend roughly 20 years in exile on average, the U.N. refugee agency reported this week. The Dabaab camp in northeastern Kenya, near the Somalia border, has existed for a quarter of a century, and many of its residents have never been home.

The United States in the past has urged Kenya’s president not to close Dadaab without stability in Somalia, which has seen decades of deadly chaos and attacks by al-Shabab.

Human Rights Watch says some of the Somali refugees have been told they would forfeit a $400 U.N. cash grant if they were deported later this year, so some leave earlier.

The rights group says many camp residents are being compelled to return to Somalia without adequate information about the dangers they face there.

Kenyan President Uhuru Kenyatta has said repatriations will be voluntary and humane. The international community has warned against forceful evictions.