Kenyan prosecutors say they are preparing to charge several students with the murder of their schoolmates following a suspected school arson attack last month.

Sixteen pupils, aged between 15 and 18, died and dozens more were injured when a fire broke out in a dormitory at Utumishi Girls' School in Gilgil, about 120km (77 miles) north-west of the capital, Nairobi.

Eight students were later arrested after police said they may have been involved in starting the fire by setting mattresses alight near an exit.

"Upon careful assessment of the evidence, the Director of Public Prosecutions (DPP) has approved charges against the implicated students," the state prosecutor's office said in a statement.

The 28 May fire tore through the upper floor of a dormitory containing 135 bunk beds and housing 202 students, forcing them to flee through a single doorway after the emergency exit failed to open.

After interviews with students and staff and a forensic review of CCTV footage, eight pupils at the school were identified as "persons of interest in connection with the planning and execution" of the fire, police said.

The suspects, who are being held in custody, are due to be formally charged in court on Friday, said the Office of the DPP on Wednesday following a court hearing in the central town of Naivasha.

"The suspects will face sixteen (16) counts of murder arising from the incident," the ODPP had said earlier.

The ODPP has expressed concern over a recent rise in cases of arson and related criminal conduct in learning institutions across the country, warning that those responsible would be held accountable.

Education Minister Julius Ogamba said preliminary findings indicated that there had been multiple breaches of safety measures at Utumishi Girls' School, including overcrowding in dormitories and a locked exit door.

Kenya has a long history of school fires - just two years ago at least 21 people died in a dormitory fire in central Kenya.

Many fires reported in boarding schools have been the result of arson, with disgruntled pupils - angry about disciplinary measures and living conditions - accused of being responsible, while others were caused by accident.

Overcrowding in dormitories and the failure to follow safety guidelines, such as keeping exits clear and windows unlocked, have frequently been blamed for the high number of casualties.