Joe Stork, deputy director of Human Rights Watch's Middle East division, said: "The high loss of life suggests the police acted with extreme brutality. A police force acting responsibly would not have allowed such a tragedy to occur."
Judicial sources said on Saturday that the toll had risen to 25 and that an inquiry had been launched. Officials said on Friday that 10 people were killed.
Egypt's Foreign Ministry defended the action, saying the UN refugee agency had sent letters to the authorities demanding intervention to end the protest.
A ministry spokesman said in a statement: "The Egyptian authorities pursued their efforts to bring a peaceful end to the sit-in by Sudanese refugees until dawn on 30 December. It was clear that certain extremist agitators among the refugees were forcibly preventing the others to leave the site.
"The migrants' leaders resorted to incitement and attacks against the police."
Ali Ahmed Kerti, Sudan's minister of state for foreign affairs, speaking to reporters in Cairo before returning to Khartoum, joined the Egyptian authorities in blaming the refugees, some of whom "sought to escalate the situation with no regard to the consequences".
Police continued to beat protest-
ers as they were taken away
He was also critical of the United Nations High Commissioner for Refugees (UNHCR) whose organisation, he said, had "promised them [the refugees] immigration but did not fulfil its promise".
Thousands of riot police using water cannons and attacking with truncheons cleared the camp. Three children were among the dead after the melee, security officials said.
Boutros Deng, one of the protest leaders at the camp, told The Associated Press 26 Sudanese were killed, including 17 men, two women and seven children.
An official from Sudan's Human Affairs Ministry said the government had offered to repatriate some of the refugees.
Abd al-Rahman Abu Dom, an adviser at ministry, told Aljazeera: "Some of them took up the embassy's offers. However, others, particularly the youth, were determined to try to migrate to European countries, but the UNHCR could not respond quickly to their demands.
"Some applications were approved while others were rejected. Rejected refugees have stayed in Cairo, and we respect our Egyptian brothers' help during their stay."
Refugees at the camp wanted
promises of resettlement
Officials at the South Centre, an independent Sudanese human rights monitoring group, said 1280 refugees were taken by bus to three locations outside Cairo.
In a statement faxed to AP in Cairo, the group said: "The savage way the security forces intervened led to a real human massacre."
The Associated Press saw police attacking the Sudanese with truncheons. In many cases, police continued to beat protesters as they were being dragged to buses.
The Interior Ministry's initial statement claimed the casualties were the result of a stampede among the refugees.
The AP saw no stampede. The protesters could not flee because the camp was encircled by police, with water cannons at each corner. Protesters could be seen fighting back with sticks.
Antonio Guterres, the UN high commissioner for refugees, expressed his shock and sadness over the deaths.
Speaking from Geneva, he said: "There is no justification for such violence and loss of life. This is a terrible tragedy and our condolences go to all the families of those who died and to the injured."
Guterres was saddened by the
refugee deaths in Cairo
The Egyptian Foreign Ministry spokesman criticised the Guterres' comments.
"It is not logical for the high commissioner for refugees to make such hasty judgments over the incidents when he himself acknowledges he does not yet know all the details," the spokesman said.
"The Foreign Ministry is also saddened and sorry for the death of some of the refugees and voices its full respect for its legal commitments towards refugees living in Egypt."
The sit-in began on 29 September after the UNHCR stopped hearing the cases of Sudanese seeking refugee status after the January peace deal that ended their home country's 21-year civil war.
About 30,000 Sudanese are registered as refugees in Egypt, and estimates of Sudanese living in that country have ranged from 200,000 to several million.
"We respect our Egyptian brothers' help during their [refugees] stay"
Abd al-Rahman Abu Dom,
Sudanese Human Affairs Ministry adviser
Egypt, which suffers from high unemployment and strained social services for its own population of 77 million, offers the Sudanese little assistance, and the Sudanese complain of discrimination by Egyptians.