Egypt has announced plans to repatriate about 650 Sudanese refugees rounded up in a violent operation last week.
The UNHCR said refugees were making unreasonable demands
Some 27 people died and hundreds more were detained when police broke up a squatter camp in Cairo on Friday.
A spokeswoman said about 650 Sudanese, found to be "illegal immigrants" or to have "violated security conditions", would be sent home by ship on Thursday.
Earlier the UN refugee agency said it had received assurances from Egypt that refugees would not be sent home.
The migrants had been camped outside UN offices since September, demanding the UN High Commission for Refugees (UNHCR) move them to a third country with better conditions.
Thousands of police wielding truncheons and firing water cannon at protesters stormed the camp before dawn.
There have been calls for the Egyptian authorities to launch an independent inquiry into the deaths.
The New York-based Human Rights Watch said: "Given Egypt's terrible record of police brutality, an independent investigation is absolutely necessary to assess responsibility and punish those responsible."
The UNHCR, though, has not backed those calls.
"We are not calling for an inquiry at this point in time," said Astrid van Genderen Stort, a UNHCR spokeswoman, quoted by the AFP news agency.
The Egyptian government explained its decision to evict the Sudanese by saying the migrants had refused orders to leave, and that the UNHCR had asked for the camp to be cleared.
Ms Stort said the UN had only asked the government to intervene after continued attempts to persuade protest leaders to back down had failed.
"Nothing that we proposed was being listened to. The demonstrators on the square wanted something impossible," she said.
"We urged the police to deal with the situation in a peaceful manner," she said, according to Associated Press.
She said the deaths were "very sad", but nobody was to blame.
"We are not blaming anyone. It went as it went and it ended in a tragic way.
"It is very sad that so many people had to die and get injured from both sides," she said.
Egypt says 74 police were injured in the operation. It says 12 protesters were killed, though morgue and hospital officials say the figure is higher.