A tweet sent by Flightradar24, a Swedish internet-based service that shows real-time commercial aircraft flight information on a map, said the plane recorded unstable vertical speed after takeoff.

The airline said 149 passengers and eight crew members were thought to be on the plane.

Eight Chinese nationals aboard

State broadcaster EBC reported that 33 nationalities were among the victims. Gebremariam said those included 32 Kenyans and nine Ethiopians. Authorities said other victims include 18 Canadians; eight each from China, the United States and Italy; seven each from France and Britain; six from Egypt; five from the Netherlands and four each from India and Slovakia.

Chinese President Xi Jinping and other Chinese leaders have sent condolence messages to the leaders of Ethiopia and Kenya.

Chinese Party and state leaders extended condolences to victims' families. and were deeply concerned with the situation of Chinese citizens involved, Lu told a regular press conference in Beijing.

"We feel deeply grieved for it. We express deep condolences to all victims and sincere sympathy to their families," Lu said.

According to Lu, the Chinese embassy in Ethiopia has established a coordination and liaison mechanism with the Ethiopian side and got into contact with the relatives of the Chinese citizens who died in the accident.

So far, the identities of the eight Chinese citizens have been confirmed.

Four are employees of Chinese companies, two work for the United Nations and the other two come from Liaoning and Zhejiang provinces.

"China hopes that the Ethiopia side can find out the cause of the accident as soon as possible and inform China of the investigation development in a timely manner, and appropriately handle the follow-up matters," Lu said.

The ministry and Chinese embassy in Ethiopia will continue to follow relevant development and make all-out effort to proactively assist the families with follow-up issues, he added.

One Chinese national, who said many Chinese prefer the flight due to its convenience to business travelers, said she was saddened and relieved at the same time. Cao Ran, who has been operating an insurance brokerage business in Nairobi for the last 10 months said she had changed her mind at the last minute and instead took a flight back on Friday. "Just a coincidence," said the owner of Jiang Tai Insurance Brokers, adding that it was a business trip.

Ethiopian Prime Minister Abiy Ahmed tweeted his condolences immediately. "The Office of the PM, on behalf of the Government and people of Ethiopia, would like to express its deepest condolences to the families of those that have lost their loved ones on Ethiopian Airlines Boeing 737 on regular scheduled flight to Nairobi, Kenya this morning."

The Addis Ababa-Nairobi route links East Africa's two largest economic powers and is popular with tourists making their way to safari and other destinations. Sunburned travelers and tour groups crowd the Addis Ababa airport's waiting areas, along with businessmen from China and elsewhere.