The BBC's World Affairs Correspondent Bob Simpson: "Scores killed or wounded"

The blasts, just minutes apart, ripped through buildings in the capital cities of Nairobi and Dar es Salaam.

The first wrecked an area around the embassy and central bank in Nairobi, Kenya.

The US State Department said both explosions were caused by bombs and blamed terrorists. But it is not known who is responsible.

Red Cross officials say that at least 60 people died in the Nairobi blast at 10.35am local time. US sources in Washington say six Americans were among the dead.

Another five people died in the explosion near the US embassy in Dar es Salaam, Tanzania.

A search for survivors continues and Kenyan police say that the death toll in Nairobi could be as high as 80 with about 1,100 injured.

US medical and security teams are flying to Africa.

The BBC's Louise Tonbridge in Nairobi: "Scenes of chaos"

There was chaos in the centre of Nairobi after the blast, which could be heard up to 10 miles away.

The Cooperative Bank building, where US Ambassador Prudence Bushnell was meeting Kenyan Trade Minister Joseph Kamotho, felt the full force.

The US ambassador was slightly injured.

Firefighters tackle the Nairobi explosion

The US embassy was also extensively damaged. Bomb-proof doors were ripped off.

Volunteers worked furiously to pull survivors from the rubble.

Rufus Drabble, from the British High Commission, said there was a cloud of thick smoke over the city and helicopters hovered overhead.

Kenyan TV had shown "horrendous" pictures of the incident, he added.

Rufus Drabble, of the British High Commission in Nairobi: "Extremely large device"

A BBC correspondent in Nairobi says private cars were used to ferry the injured to city hospitals.

He says that radio reports from inside the US embassy called for medical help and lifting gear.

Hundreds of people reportedly fled the building as emergency services and armed police raced to the scene.

The bank building, on Haile Selassie Avenue, contains private and government offices.

Tanzania blast

There was also widespread devastation in Dar es Salaam, where a BBC correspondent said the embassy reception area had been destroyed.

Ian Gleeson: "Likely to have been a bomb"

Ian Gleeson, from the British High Commission in Tanzania, said: "In view of the news from Nairobi it seems very likely that it was a bomb."

He said British diplomats had offered to help the US embassy and the French and Spanish embassies, which are also near the site of the explosion.

Survivor Jim Owens said the blast at the Tanzanian embassy threw him back about five feet.

Survivor Jim Owens: "Smoke-filled embassy"

He said: "The cuts I have do not look that bad but they bled profusely.

"They bled over my glasses so I couldn't see as I was walking around the smoke-filled embassy."