First they came for his father, then they told Abdirahman Sharif Mohamed that they were coming for him.

In a series of chilling telephone warnings, militants from Somalia’s notorious al-Shabaab movement denounced the father of six as a traitor and ordered him out of Mogadishu.

“They said they would kill me if they found me,” he said. “They told me since I was working for the Government they wanted me dead.”

Hundreds of people are crossing Somalia’s border with Kenya every day as they flee the Islamist militias who have brought a fresh round of terror to an already dysfunctional country.

Families who stayed through 18 years of strife have had enough.

Almost 170,000 people have left the capital, Mogadishu, in six weeks of fighting that has raised brutality to new levels — even by Somalia’s standards. Amputations, kidnappings and murder are the tools of war.

Mr Mohamed arrived in Dadaab, northeast Kenya — the world’s largest refugee camp — this week after a fortnight hitching rides and walking to the border. “I was born in Mogadishu and decided to work for the Government,” he said, sitting on a rickety bench outside United Nations huts, where he was waiting to register as a refugee. “It made me proud. It was my duty.”

The digital watch on his wrist was a symbol that he was a man of means. Earning $2 (£1.21) a day meant that he could look after his family and help to rebuild Somalia.

However, after the fifth menacing telephone call from the Islamist militants he decided that it was time to run. His father had been kidnapped and then executed and he feared that he would be next.

There are dozens of similar stories among the families gathered around the simple UN huts where they register for vaccinations, food and shelter. Wives have arrived without their husbands, not knowing if they are alive or dead. Everyone has lost loved ones or watched friends shot dead.

The latest fighting pitches the Islamist al-Shabaab movement against an interim Government which has struggled to assert any authority since being formed in 2004.

A moderate Islamist, Sheikh Sharif Sheikh Ahmed, won the presidency this year. Three years ago his Union of Islamic Courts brought stability to Somalia before being defeated by Ethiopian troops.

His Islamist background raised hopes that extremists could be brought back into the fold — hopes that have so far not been realised. Al-Shabaab, considered by the US as a terrorist outfit with links to al-Qaeda, has taken over swathes of Somalia, as much through deals with local clan leaders as through force.

This week its militants punished four men convicted of stealing mobile phones and guns by cutting off a hand and a foot each. Two hooded men applied tourniquets before using a traditional curved sword to carry out the sentence of a Sharia court. Hundreds of onlookers jostled to watch the bloody spectacle in Mogadishu.

At the same time the State Department confirmed that the US was sending arms and ammunition to the Government and would also help to train its troops to fight the Islamist insurgents.

Dadaab — actually three camps in one — stands as a miserable testament to the world’s failure to find a solution to Somalia’s strife.

More than 280,000 people are crammed into a congested jumble of mudbrick homes and tents. When it was opened in 1991 no one believed Kenya would still be hosting Somali’s refugees almost two decades later.

Today it is more of a city than a camp. Tangles of wire carry electricity from thrumming generators to internet cafés, cinemas showing Bollywood movies and kiosks selling mobile phones — all run by refugee entrepreneurs.

Its boreholes are stretched to breaking point and aid workers fear outbreaks of disease if the sprawling site’s 35,000 latrines are not renovated. Every day the camp generates 300 tonnes of waste — mostly animal droppings from thousands of goats and camels — that need to be removed.

The UN is trying to find more land to accommodate the 500 people arriving every day but faces resistance from a Government wary of the arrivals.

The European Commission is giving €11 million (£10 million) this year to try to ease conditions. “More people are coming every day so we have got to make sure the system is working,” said Daniel Dickinson, a spokesman for its aid arm, Echo.

And there are still the first wave of refugees, those who arrived with the collapse of the Government in 1991, who know they have little prospect of going back.

Saharo Sheikh Mohamed has not left the camp in 18 years. Her dream is to be one of the lucky ones chosen to be resettled in the US. “We would prefer any country where we could live peacefully,” she said.

Times Recommends

• Would you live on the wrong side of the Berlin Wall?
• Wish you were here, says Iraq tourist board
• Russian policeman’s corruption plea to Putin