There were no survivors from an Ethiopian Airlines flight that crashed with 149 passengers and eight crew members aboard, the state broadcaster said on Sunday.

"There are no survivors onboard the flight, which carried passengers from 33 countries," said state-run Ethiopian Broadcasting Corporation, quoting an unidentified source at the airline.

The Boeing 737 passenger jet "had unstable vertical speed", Swedish flight-tracking website flightradar24 said.

"Data from Flightradar24 ADS-B network show that vertical speed was unstable after take off," the Swedish-based flight tracking organisation said on its Twitter feed.

The Ethiopian prime minister's official Twitter account on Sunday expressed condolences to families of those lost in an Ethiopian airline's flight to Nairobi, without giving details.

"The office of the PM, on behalf of government and people of Ethiopia, would like to express it's deepest condolences to the families that have lost their loved ones on Ethiopian Airlines Boeing 737 on regular scheduled flight to Nairobi, Kenya this morning," the PM's office said on Twitter.