NAIROBI (AFP) - Investigators in Kenya were on Saturday questioning the police and airport workers suspected of taking advantage of a fire at Nairobi's main airport this week to steal cash and alcohol.

"It is embarrassing because some of them concentrated on looting instead of raising alarms," said a police officer on the investigating team who requested anonymity.

"We're questioning all of them. Police officers, immigration staff, civilians who work in other areas and even taxi drivers," he added.

Security cameras had caught some thieves in action, he said.

Kenyan newspaper Daily Nation reported that seven police officers were being held for suspected looting and could appear in court on Monday. The men were found with cash and alcohol on them, allegedly stolen from the airport shops that were destroyed in the blaze, the paper said.

The cause of the fierce fire which broke out at 5am local time at the international terminal at Jomo Kenyatta International Airport (JKIA) on Wednesday, and which blazed out of control for several hours, has not yet been determined.

The airport's main arrivals hall was gutted in the blaze, which took firefighters around four hours to bring under control, hampered by a lack of both water and equipment.

President Uhuru Kenyatta has ruled out terrorism.

"There was no element of terror, no evidence of explosions or improvised explosive devices in this incident," he said on Friday on a visit to the airport.

But he warned that "those responsible for negligence will have to be punished".

On Saturday an investigator indicated that the fire could still be the result of arson.

"Given our questioning of witnesses and employees it is difficult to exclude (the possibility of) a deliberate fire," said the source, who wished to remain anonymous. He did not give any further details on potential suspects or their motives.

Investigations were continuing "with the help of security from other friendly nations", the President said on Friday.

A police source who asked not to be named said that Kenyan investigations were benefiting from the "help of partners, including (America's) FBI".

The fire broke out 15 years to the day after the twin bombings by Al-Qaeda targeting the US embassies in Nairobi and in the Tanzanian economic capital Dar es Salaam that left 224 people dead.

The airport blaze caused no casualties but paralysed operations on Wednesday at the principal aviation hub for east Africa. International and domestic flights were subsequently cancelled.

Mr Eric Kiraithe, head of security at JKIA, said on Friday that most of the airline companies were operating normally again.

According to the Kenyan authorities, some 16,000 passengers transit every day through JKIA.

August is one of Kenya's busiest months for tourism, a key industry for the country, as foreign travellers fly in to see its wildlife and enjoy the white sand beaches on its Indian Ocean coast.

Mr Kenyatta has said the authorities would build a temporary terminal, which would be ready "in the coming weeks".