Kenya's education minister said on Monday that arson was to blame for a weekend blaze that killed nine pupils at a girls' boarding school, part of a rising trend of deliberate school fires.

"It was not an accident, it was arson," Minister Fred Matiang'i said of the fire on Saturday at Moi Girls School in Nairobi.

The Kenya Red Cross said on its Twitter feed there had been three other school fires reported in different parts of the country on Monday.