Firefighters were struggling on Wednesday to contain a raging blaze that has forced the closure of Jomo Kenyatta International Airport in Nairobi, witnesses and officials said.

The fire at east Africa's busiest airport started at around 5 a.m. (0200 GMT / 10:00 p.m. Tuesday EDT) in the immigration section of the departure lounge and spread to the international arrivals area, a Kenya Civil Aviation Authority official said on condition of anonymity.

"No planes are departing or arriving - only emergency landings will be allowed," the official said.

The fire comes less than 48 hours after a fuel jet pump failure caused huge delays at the airport, forcing some flights to be rerouted to the airport in the coastal town of Mombasa, Entebbe International Airport in Uganda and Kigali International Airport in Rwanda.