Questions over NY explosion: One week after a blast rocked Manhattan, killing five people, detectives have discovered how it was done but have no idea why it was done

IT WAS the first Friday in Ramadan, the Muslim month of fasting, when, according to New York authorities, a man named Mohammed Salameh helped plant the bomb that went off last week beneath the World Trade Center.

Why would an observing Muslim have chosen such a day? Ramadan is one of the four months of the year when Muslims are not meant to go to war (although president Sadat launched his forces across the Suez Canal in October 1973 on the tenth day of Ramadan).

Sheikh Omar Abdel-Rahman certainly condemned the act. No true Muslim would have performed it, he said. Even though, according to the FBI, Mr Salameh had worshipped at Sheikh Omar's mosque in Jersey City. The blind Egyptian preacher, who is imam of the Majlis al-Salam, the Mosque of Peace, in Jersey City, 'unequivocally denounced the bombing' of the World Trade Center.

In a statement, he declared that 'Islam is opposed to the destruction of life and property of the innocent. The bombing of the World Trade Center could not have been done by a true Muslim.'

Sheikh Omar is one of the key figures in militant Islamic circles. From the comfortable and politically tolerant atmosphere of Jersey City, he could broadcast his virulent anti-Western sermons to his followers among militant Muslims in Egypt through tape recordings. Some of those who heard his message that tourism in Egypt was harmful have been behind the attacks on foreign tourists in Egypt over the past months.

During his trial with 23 others accused of the assassination in October 1981 of Sadat, Sheikh Omar emerged as a lost and rather pathetic figure. He was released, picked up and accused on other related charges, then acquitted once more. He later set up a preaching base in Fayoum, south of Cairo, and came to the United States in 1990.

And his mosque has been cited as the place of worship of at least one other Muslim extremist accused of an act of violence. In 1991 Sayyed Nosair was acquitted of assassinating the founder of the Jewish Defence League, Rabbi Meir Kahane.

Sheikh Omar denies any connection. And there is little apparent reason why foreign powers or other organisations would have been behind the bombing.

But what motive can any Muslim extremist have had in planting a bomb beneath the tower? And if there was a political motive, why was no statement released claiming responsibility?

There is considerable frustration among militant Muslims who are keen to prove to the outside world in general and the United States and the West in particular that they cannot be immune from the consequences of what is happening to the Muslims in Bosnia, and the 400-odd Palestinians deported by Israel in December.

The mood is hardly propitious in the US at present to take a merciful view of Islamically inspired acts of political violence. The means deployed - a huge car bomb - is reminiscent of methods used in the last significant acts of violence against American targets, namely the attacks on the US embassy and the Marine barracks in Beirut. There may be no connection between the World Trade Center and the Palestinian Hamas movement, but the context exists.

On Thursday, a bill to ban members of the Islamic Resistance Movement, Hamas, active in the Israeli-occupied West Bank and Gaza strip, was introduced in Congress.

It was tabled by Senator Alfonse D'Amato, a Republican from New York, who said: 'We cannot allow the United States to serve as a base for members of this murderous terrorist organisation.'

Earlier in the week the State Department announced that it had instructed its diplomats to cease contacts with Hamas. And a section on Hamas is included for the first time on the annual State Department publication, Global Patterns in Terrorism. Yet Hamas, despite its charter calling for the destruction of the state of Israel, has generally targeted Israeli soldiers within the occupied territories. The kidnapping of an Israeli soldier, Nissim Toledano, in Israel proper (who was later murdered) was out of the usual pattern.

For their part, the Israelis have sought to demonstrate that the organisational structure of Hamas is based in the US. It is certainly in Israel's interest to show that after the collapse of Communism, militant Islam has emerged as the ideological enemy of the free world.