They chant of bitterness and hell

We are the Awaleq

Born of bitterness,

We are the nails that go into the rock.

We are the sparks of hell.

He who defies us will be burned.

THUS RUNS the tribal chant of the Awaleq, one of Yemen's most powerful tribes. Nor are they alone in their fierceness. In the mountains of Abyan province, east of Aden, are the Kazam, a warlike tribe famous for their generous hospitality to strangers arriving in their lands.

But the well-fed guest should be wary as he bids farewell to his hosts. Once he travels out of their territory, the tribesmen of the Kazam consider him fair game. The laws of hospitality no longer apply. He becomes, in their own phrase, "a good back to shoot at" and the Kazam are known locally for the excellence of their marksmanship.

Neither the Awaleq nor the Kazam are exotic remnants on the margins of Yemeni society. The central government in the capital, Sanaa, with little real power of its own outside the main cities, is wary of offending them. In one of the poorest countries in the world, it wages a constant battle to assert itself against a host of rivals who may have a tribal, political or religious base.

The city of Aden and the countryside around it is full of signs of this conflict. The airport roof is supported by freshly rebuilt raw concrete columns, repairing the damage caused by bombing during the Yemeni civil war in 1994, when the south of the country, united with the north only three years before, tried to secede with the backing of Saudi Arabia.

The political legacy of the war is a constant topic of conversation in the former British protectorate, where the domination of officials from the north is deeply resented. One well-informed Yemeni observer said: "I think the hatred now is greater than it was during the war."

Leaving Aden to the east along the Chinese-built coast road, there are a few holiday chalets under construction on the seashore to the right, but nothing to the left where there are extensive mine fields. On the outskirts of the city there is a shanty town, home of some of the 850,000 Yemeni workers expelled from Saudi Arabia in 1990 when Yemen took a neutral stance after the Iraqi invasion of Kuwait. Their expulsion devastated the Yemeni economy, which has never recovered.

The coast road is considered safe from kidnappers but, further north in Abyan province, 16 tourists were kidnapped in December by Abu Hassan, the Islamic militant now on trial, and four tourists, three Britons and an Australian, were killed during a rescue attempt.

This was a shock: no foreigner had been hurt in more than 100 kidnappings by the tribes. None the less, hostage-taking has become a recognised way of putting pressure on the government. Yemen is famous in the Arabian peninsula for the quality of its honey. Hives were traditionally kept in hollowed-out tree logs on metal stilts to protect them from ants. A year ago the police angered one tribe by destroying some of its prized hives. The tribe demanded compensation from the government. When nothing happened they put up a checkpoint on the main road and kidnapped a Chinese person to underline their grievance.

The central government is weak, but Yemen is also more democratic than most of the Arab world. There is an embattled but vigorous opposition press. When Abu Hassan, the kidnapper, was put on trial earlier in the month, state-owned Yemeni television broadcast 45 minutes of his tirade from the dock against the government.

Into this violent, anarchic and suspicious world eight British Muslims and two Algerians with French passports entered last year. They say their purpose was the innocent study of Arabic and Islam. The prosecution at their trial in Aden which resumed yesterday says their real aim was to form the "Aden cell" of the Supporters of the Sharia (Islamic law), the group formed by Abu Hamza al-Masri, the militant Islamic cleric of Finsbury Park, north London.

It was not a visit likely to end well. Two of the eight Britons now under arrest in Yemen are related to Abu Hamza who openly denounces the Yemeni government as not fully Muslim because it does not follow Islamic law. One is his stepson Mohsin Ghalain, a rusty haired 18-year-old student, and the other his full son Mohammed Mustapha Kamil, also 18, who was arrested last week. A third member of the group is engaged to marry Abu Hamza's sister-in-law.

In a suspicious country, these relationships were bound to cause suspicion, even if the intentions of the visitors from Britain were entirely academic and religious. There is reason to think that the suspicions grew early.

Yemeni sources have told The Independent on Sunday that their investigation started in early December when they detained but later released, after 10 hours of interrogation, a Yemeni named Mohammed Nader at Aden airport.

But it was the kidnapping by Abu Hassan of the tourists on 28 December which turned the arrests in Aden four days earlier into a cause celebre. When it was revealed that he had used his mobile phone from his scrubland encampment to seek advice from Abu Hamza in London, the Yemeni government saw a triangular conspiracy. The fanatical sheikh in London, the kidnappers in Yemen with whom he was in contact, and the group in Aden strongly linked to him by family ties.

"Perhaps they found a string and are trying to turn it into a rope," said one Yemeni. Torture is routine in Yemeni jails. As a Yemeni saying about such interrogations has it: "They can make a zebra say he is a gazelle."

In some respects, Yemen has managed to get the worst of all possible worlds. It freely allowed television cameras into the courtroom - but got no credit for this because pictures of men with marks of torture were immediately flashed around the globe.