The interim president of Kyrgyzstan has said the number of deaths in the unrest in the south of the country could be "several times higher" than the official death toll which currently stands at 178.
Roza Otunbayeva said on Tuesday that the number had to be higher, due to the Muslim tradition of burying the dead the same day.
Mass graves have been dug in the city of Osh, where the violence started on Thursday.
More than 1,800 people have been injured, according to official figures.
"The number of those killed in the violence in Osh was 132 people, with the total of the injured rising to 1,333. In Jalal'abad, 46 people are dead and a total of 533 injured," the health ministry's press centre said.
But the International Committee of the Red Cross echoed claims of a higher death toll.
"According to the team on the ground, several hundred people have been killed in the fighting, although it's still too early to say precisely how many as a number of bodies have already been buried and may not have been identified or counted, while others remain uncollected," the ICRC said in a statement.
Aigul Sigulina, a spokeswoman for the ICRC in Bishkek, told Al Jazeera: "We think that the number of people killed is higher than reported in the media because we have seen massive amounts of people buried.
"Medical workers have been attacked and beaten, ambulances have been damaged. Even our operations sometimes had to stop because we were going to a hospital and were blocked by shootings and we had to go back."
Meanwhile, suspicion was growing that the fighting between ethnic Uzbeks and Kyrgyz had been deliberately ignited.
The United Nations said there was evidence that the violence was co-ordinated and began with five simultaneous attacks in the city of Osh.
Rupert Colville, spokesman for the UN High Commissioner for Human Rights, said "it might be wrong to cast it, at least in origin, as an inter-ethnic conflict.
"There seems to be other agendas driving it initially."
He told a news briefing in Geneva that the UN human rights office had collected witness accounts, including from UN staff, in the cities of Osh and Jalal'abad.
"Several of these reports suggest that the incident began with five simultaneous attacks in Osh involving men wearing balaclavas and carrying guns. It looked like they were seeking to provoke a reaction," he said.
Colville said that one of the attacks was on a gym which he said was "known to be the haunt of a criminal gang".
"Targeting that gym was likely to provoke a reaction."
The UN was not in a position to make any direct accusations against any particular individuals or groups at this point, Colville said.
Witnesses have said the unrest started with mobs of Kyrgyz men attacking ethnic Uzbeks and torching their homes.
The interim government, which assumed power after the president was overthrown in April, has repeatedly accused Kurmanbek Bakiyev, the ousted president, of stoking the conflict.
Otunbayeva told Al Jazeera on Tuesday that she had "no doubt" Bakiyev was to blame.
"His sons have been discussing that they want to organise such a crisis and we thought not of such a scale and not of such a deepness," she said.
About a month ago, an audio recording was posted anonymously on YouTube with a caption identifying the voices as those of Bakiyev's son Maxim and his uncle Janybek.
The men were discussing plans to arm groups to spread chaos across the south of Kyrgyzstan, sometime in June.
Both men have denied the authenticity of the tape and Bakiyev has repeatedly said he has no involvement in the violence.
The interim government has accused Maxim Bakiyev of financing the ongoing clashes.
Kyrgyzstan's 5.3 million population is mainly made up of Kyrgyz (70%) ethnic Uzbeks (15%) and Russians (8%).
About 50% of the Osh region's 1.2 million inhabitants are ethnic Uzbeks.
About 40% of a population of one million in Jalal'abad region are ethnic Uzbeks.
"This was all well organised, and the 'wallet' of these riots is the son of the former president, Maxim Bakiyev, who started financing the riots back in April," Atambayev, the deputy interim leader, said at a news conference.
The younger Bakiyev is said to have paid $10 million to organise the fighting. He was arrested by UK authorities on Monday as he landed at Farnborough airport in a private aircraft.
The Kyrgyz government said it would seek his extradition.
Tens of thousands of ethnic Uzbeks have fled fighting in the provinces of Jalal'abad and Osh.
The office of the UN High Commissioner for Refugees (UNHCR)
said 200,000 people had been displaced within the country in addition to 75,000 who had crossed the border into neighbouring Uzbekistan.
Uzbekistan closed the border on Monday to all except those with fresh wounds or special needs, saying it did not have resources to cope with the mass exodus.
It reopened three checkpoints to let in more than 60 wounded people late on Tuesday.
Medics in the Uzbek Andijan border region are struggling to treat the flood of refugees.
"We treated today a 28-year-old man who was tortured. He had signs of knife wounds on his neck, burned skin from scalding water and had been shot. We took out the bullet," Kozim Mahkamov, a doctor, said.
Another doctor said three sisters, aged between 16 and 23, had been raped in front of each other by a mob of Kyrgyz men.
"These girls were raped recently and by a lot of men and for several hours, according to their injuries," Mukaddas Majidova told AFP.
Schools and other public buildings have been transformed into makeshift refugee camps.