"The alleged torture claims were investigated by the (ministerial) committee and the criminal prosecutor," Justice Minister Salah Bashir said in an interview with the pro-government dailies Al-Rai and Jordan Times on Monday.
"We are taking this incident very seriously. Those found involved in this incident will be legally prosecuted," said Bashir who heads the ministerial committee set up after the incident.
"The rule of law will apply on everybody, regardless of their status," he added, without disclosing the findings of the inquiry.
According to the National Centre for Human Rights (NCHR), Abd Allah al-Mashabka died on 1 September at Juwaida prison, south of Amman, as a result of "torture and abuse" during a brawl between guards and inmates.
The NCHR was founded two years ago by a royal decree and is currently headed by former Prime Minister Ahmad Ubaidat.
An NCHR report submitted recently to the authorities protested of "serious human rights violations" in Jordanian prisons, according to excerpts published on Monday in newspapers.
Inmates are subjected to "beatings and lashings as well as suffering from other human rights breaches", the report said.
Inmates are subjected to "beatings and lashings as well as suffering from other human rights breaches"
National Centre for Human Rights, Jordan
But Bashir said in the interview: "I don't believe these are systematic practices by prison guards.
"I believe one of the major problems at Juwaida prison is overcrowding. The capacity is about 1000 inmates but we found 1600 on one visit," he said, adding that steps would be taken, including speeding up court proceedings.
Government spokeswoman Asma Khudr told Al-Rai the incident was "an isolated act which does not represent a general policy".
"The government ... is determined to apply the law and punish anyone responsible for breaking the law, either inmates of prison guards," she said.
Several cabinet ministers and representatives of non-government organisations and human rights groups met on Sunday the director general of the public security department to discuss prison conditions in Jordan, the press said.
Bashir and Interior Minister Samir Habashna also paid a "surprise" visit to Juwaida prison on Friday, the justice minister said.