Two people have died in detention in Mali after being tortured by the military and denied ventilation in a cell, a rights group has said.
One of them had expressed fears of dying "from the heat" in temperatures likely to be higher than 38C (100F), US-based Human Rights Watch (HRW) said.
The men were ethnic Tuaregs accused of supporting Islamist militants recently ousted from northern Mali, it said.
Officials in Mali have not yet commented on the allegations.
France intervened in Mali in January to help the weak Malian army recapture the vast northern desert region from the Islamist militants.
The Islamist groups had formed an alliance with Tuareg separatists early in 2012 to capture territory from the government in the wake of a coup.
But the alliance quickly collapsed, and the Islamists drove out the Tuareg separatist group - the National Movement Liberation of Azawad (MNLA) - from the main cities and towns in the north.
Since the French-led operation many Tuaregs have complained of being targeted by Malian soldiers who accuse them of backing the rebellion.
'Burned and injected'
In January, the International Federation for Human Rights said there was "credible information" that at least 20 Tuaregs and people of Arab origin had been summarily executed by Malian soldiers.
The Malian army said at the time that it was investigating the allegation.
HRW said the detainees who died were part of a group of seven Tuaregs seized by soldiers on 15 February in the northern town of Lere.
They told a HRW researcher that they had been beaten, burned, injected with a caustic substance, and threatened with death while in army custody.
The men were transferred to the central prison in the capital, Bamako, HRW said.
"People who knew the two men told Human Rights Watch that they died during the night of 6 and 7 April as a result of excessive heat, possibly combined with the injuries from their earlier mistreatment. The torture may have left them vulnerable to rapid deterioration," the group said in a statement.
The men had been detained in a room with no ventilation, even though the average temperature in the city at this time of the year is higher than 38C, it added.
"Temperatures within an enclosed room without ventilation would drive this temperature considerably higher. The witness [who spoke to HRW] quoted one of the detainees who later died as saying: 'If we are not moved from that room, all of us are going to die from the heat,'" the statement said.
HRW called on the government to investigate the deaths and improve both the treatment and conditions of all its detainees.