An airline official said rescue teams were trying to find the site of the crash, and there was no immediate word on any casualties.

"We are trying to get to the area of the crash, but the weather is really bad. We are getting help from the army," a Kenya Airways official told AFP in Cameroon.

Air traffic controllers picked up a distress signal from the missing airliner just after it took off from Douala during a violent storm, a source linked to the Agency for the Safety of Aerial Navigation in Africa said.

Two Cameroonian army helicopters began searching a wide area south of the line between Douala and the capital Yaounde, 250 kilometres (180 miles) to the east, to try to locate the aircraft.

"The plane has crashed," an official with the Kenyan Civil Aviation Authority, who asked not to be named, told AFP.

However, the chief executive officer for Kenya Airways, Titus Naikuni, said he could not confirm the crash.

Speaking at a news conference in Nairobi, he revised an initial figure of 115 on board to 114, comprising nine Kenyan crew members and 105 passengers.

Including the crew, there were 79 Africans of various nationalities, 15 Indians, six Chinese, five Britons, one Swiss, one Swede and one US citizen, and another six who had not been identified, Naikuni said.

Flight KQ 507, a Boeing 737-800 only six months old, was flying from Abidjan in Ivory Coast via Douala to Nairobi, where it was due at 6:15 am (0315 GMT).

Most of the passengers were connecting through Nairobi to other destinations outside Kenya.

"As far as I know, the aircraft is updated in terms of maintenance and the pilots are also updated in terms of training," Naikuni said.

Cameroonian authorities set up two emergency centres, one in Yaounde and the other in Douala, to coordinate search operations, and a crisis centre has been established at Kenya Airways headquarters at Nairobi airport.

Some 10-15 people were waiting at the arrivals section of Nairobi airport early Saturday, guarded by several police officers.

"We have been told to sit and wait," said one relative of a passenger on the plane. "A lot of people are crying, people are asking what is happening."

Other concerned relatives gathered at a crisis centre in a Nairobi hotel.

"They are not telling us anything ... I do not know whether my daughter was supposed to fly back from west Africa today or tomorrow," said the mother of an air stewardess, sobbing. "I have given my number and I just have to wait."

"It is a great tragedy for all of us in this country," said Kalonzo Musyoka, former Kenyan foreign minister, speaking at the hotel.

The Kenyan government was "saddened" by news of the missing flight, spokesman Alfred Mutua told a news conference earlier.

"We have activated all relevant government departments in the search and rescue of the missing," Mutua said.

"The government will do everything to unearth the cause of this accident in order to prevent it from occurring again."

Transport Minister Chirau Ali Mwakwere was due to go to Cameroon and link up with authorities there.

In January 2000 a Kenya Airways Airbus crashed into the sea after taking off from Abidjan airport, killing 169 passengers and crew.

Air France-KLM owns 26 percent stake in Kenya Airways, which prides itself on its reputation as a reliable African air company.

Kenya Airways was to hold a second news conference at 3.00 pm local time (1200 GMT).

A local passenger information centre has been opened at the Intercontinental Hotel in Nairobi and an international contact number has been set up on: +27 11 2071100.