An Ethiopian Airlines jet has crashed shortly after take-off from Addis Ababa, killing all on board.

The airline said 149 passengers and eight crew members were on flight ET302 from the Ethiopian capital to Nairobi in Kenya.

The cause of the crash is not yet clear. However, the pilot had reported difficulties and had asked to return to Addis Ababa, the airline said.

“At this stage, we cannot rule out anything,” Ethiopian Airlines CEO Tewolde Gebremariam told reporters at Bole International Airport in Addis Ababa.

“We cannot also attribute the cause to anything because we will have to comply with the international regulation to wait for the investigation.”

Gebremariam told the news conference that passengers from more than 30 countries were on board the flight.

The crash happened at 08:44 local time, six minutes after the months-old Boeing 737 Max-8 took off.

Visibility was said to be good but air traffic monitor Flightradar24 reported that the plane’s “vertical speed was unstable after take-off”.

An eyewitness at the scene told the BBC there was an intense fire as the aircraft hit the ground.

“The blast and the fire were so strong that we couldn’t get near it,” he said. “Everything is burnt down.”

First word of the crash came when Prime Minister Abiy Ahmed expressed his “deepest condolences” on Twitter.

In an earlier statement, the airline said that search and rescue operations were under way near the crash site around the town of Bishoftu, which is 60km (37 miles) south-east of the capital.