The abuses were part of a police crackdown that began the day after an attack on a crowded bus in the Somali-dominated suburb of Eastleigh, which killed seven people, HRW said. No one claimed responsibility for the blast.

Kenya has experienced a series of gun and grenade attacks since it sent its soldiers into Somalia in 2011 to drive out the Islamic militant group al-Shabaab.

Police raped, assaulted, robbed and arbitrarily detained Somali and Ethiopian refugees and asylum seekers, as well as ethnically Somali Kenyan citizens, HRW said.

"Every person we interviewed said the police accused them of being terrorists and then extorted money from them," Gerry Simpson, the report's author, said at a press conference.

Kenyan police did not respond to repeated calls for comment on the report, which was based on 101 interviews and is HRW's fourth in four years documenting Kenyan police abuse of Somali refugees.

The government spokesman also was not available to respond to the report.

The report said the scale of the latest crackdown was "unprecedented". Somali women described being gang-raped by policemen, and people were beaten on the streets, in trucks or in their homes until they lost consciousness, spat blood or broke bones, it said.

Refugees said they were detained for days in police cells without explanation until they paid bribes.

"Personal gain — not national security concerns — was the main reason police targeted and abused their victims," the report said.

HRW said the police were emboldened by a December government directive ordering an estimated 100,000 urban refugees to move to two camps on its northern borders.

In January, the High Court blocked the planned relocation. At this point, the abuses ended, HRW said. The court is due to rule on the legality of the directive in June.

Many refugees have lived in Nairobi for decades where they can own businesses, attend school or receive medical treatment. None of these opportunities are readily available in the refugee camps, which are severely overcrowded and lack basic services.

The Kenyan government has repeatedly said that it would like the Somali refugees to return home as soon as possible.

HRW called on the Kenyan government to investigate and discipline those responsible to deter future abuses.

Simpson said that Nairobi refugees are living in fear.

"There is clearly anticipation of further violence if Kenya's political leaders decide they want to move people from the cities or force them back to Somalia," he said.

(Reporting by Katy Migiro; Editing by George Obulutsa and Sonya Hepinstall)

link http://www.reuters.com/article/2013/05/29/us-kenya-refugees-torture-idUSBRE94S0NS20130529