John Bown and Blair Davies, who are part of a government-backed task- force working in Ethiopia training the country's police officers in a range of skills - including personal protection - were dining with their wives and a fifth Briton in Blue Tops, a popular restaurant in the city, when a grenade was thrown through the window.
To protect their wives and other diners, they threw themselves on to the grenade as it went off. The blast rocked the restaurant, sending shards of glass and shrapnel flying through the air.
The two men were the most seriously injured of the casualties in the explosion on Saturday night and were treated in hospital for multiple lacerations. Their wives, the other Briton and a French couple suffered minor wounds and shock in the attack - one of three in the capital on Saturday which left one woman dead and about 40 people injured.
A spokesman for the Foreign Office said the two Britons were taken to the city's Black Lion Hospital, where they were in a stable condition.
A British embassy spokeswoman, Janet Duff, said: "Most of the injuries were due to flying glass and shrapnel, but we don't think anybody is in danger of losing their life. Obviously the injured are in a great amount of shock and emotional turmoil. I think everyone here is very shocked and it will remain tense over the next few days." There was no evidence, she added, to suggest the men were targeted because they were training the police.
The manager of Blue Tops later said he saw three men enter the restaurant and after a brief conversation with the waitress, they threw two grenades at the eight diners inside.
A terrorism expert, Professor Paul Wilkinson from St Andrew's University, praised the "courage and professionalism" of the men, saying they reacted with speed and selflessness to prevent further tragedy.
There have been several bombs in Ethiopia in recent months. British, French and German tourists were injured in February last year in a grenade attack on a hotel in the ancient walled city of Harar in the east of the country.
The Overseas Development Administration confirmed yesterday that the men injured in Saturday's blast were involved in a pounds 4.9m training project aimed at completely restructuring the Ethiopian police force.
The British Embassy said the men were working for private companies which help provide international training to people working in the public sector.
Professor Wilkinson said the valuable work of such training teams is often not appreciated by the public.
"These teams regularly go abroad and their record is excellent. Inevitably this work leads them into danger. This incident reveals the incredibly high calibre of some of the people involved."
The Ethiopia scheme had been running for four years and was due to end this year.
An ODA spokesman said: "The basic idea of the scheme is to restructure the Ethiopian force along civilian lines. After the end of the civil war there they had more of a paramilitary set-up."Reuse content