Four found guilty of Trade Center bombing: Peter Pringle in New York says the hunt goes on for the man described as the 'evil genius' behind the plot

A YEAR after a van bomb blasted a five-storey cavern in the foundations of the World Trade Center, killing six people and injuring more than a thousand, four Islamic militants were yesterday found guilty of plotting the most devastating act of terrorism on United States soil.

As the verdicts were announced on the fifth day of the jury's deliberations, one of the convicted men, Mohammed Salameh, yelled: 'Allah Akhbar' and 'Victory to Islam' in Arabic. The men nodded to each other as if they had expected to be found guilty. They now face life imprisonment.

The four are Ahmad Ajaj, who brought his manuals on bomb-making and terrorism to the US; a chemist, Nidal Ayyad, who ordered some of the materials used; Mohammed Salameh, who rented the van that carried the bomb; and Mahmud Abouhalima, who was brought back by the FBI from Egypt where he had fled.

After a trial that lasted five months and featured mind-numbing detail about bomb materials and motor vehicle parts, the jury took five days to find the four guilty. The verdict was based on circumstantial evidence of a conspiracy; none of the suspects was ever placed by witnesses, or forensic evidence, at the scene of the crime.

The FBI investigation into a wider plot by Islamic extremists to target New York landmarks is far from over. A second trial of another cast of conspirators will begin in September. Those charged include the blind Egyptian cleric, Sheikh Omar Abdel-Rahman, and 14 others, all accused of plotting to blow up the United Nations headquarters and other New York landmarks. The sheikh, who speaks only Arabic, is to conduct his own defence.

Still at large from the first trial is Ramzi Yousef, the man described during evidence as the 'evil genius' behind the plot. He may hold the key to the mystery of how this motley crew came together and decided to launch a bombing campaign. Washington is offering a dollars 2m ( pounds 1.3m) reward for Mr Yousef and a similar reward for an alleged accomplice, Abdul Rahman Yasin, who has fled to Iraq.

So far, one can only guess at the motive: a belief in the cleansing power of the jihad (holy war) or compliance with a standing order to harm the 'Great Satan', the United States. The FBI has considered that the bombing might have been revenge for the Gulf war. The blast occurred on 26 February last year, which was the second anniversary of the day allied forces encircled and destroyed the Iraqi army.

The plotters, who did not give evidence, were painted as servants of an absent master. But who? The blind sheikh, who was jailed and tortured by Egyptian police for the murder of President Anwar Sadat, is today a constant critic of President Hosni Mubarak, but he has disclaimed any hatred of the United States which he describes as 'a country I chose to come to, whose people are very generous'.

How generous Americans remain to foreigners is a question under constant review. Many would blame immigration of undesirables, of course. Their present fear is that there will be some Islamic revenge on US soil, probably New York, for the Brooklyn man, Baruch Goldstein, from Brooklyn, who killed 43 Palestinians in a Hebron mosque in the West Bank last Friday.

Meanwhile, New Yorkers have been counting the cost of the World Trade Center blast. The insurers' bills for repairs to the underground garage and hotel complex are estimated at dollars 550m.