In the early days of the war in Bosnia, when the mostly Muslim population of Sarajevo was first besieged by Bosnian Serbs, Saudi Arabia's ambassador in Britain, Ghazi al-Gosaibi, wrote a poem and distributed it to Arab diplomats.

"O people of Sarajevo," it said, according to an unofficial translation. "If you were Christians, armies of bishops would have come to your rescue. If you were Jews, the blood of the Serbs would have run in the valleys."

Three years later, the Muslim world is increasingly, and openly, embracing the image of the Bosnian conflict implicit in Gosaibi's verse: The war is a new Crusade, everyone else is hostile to the Muslims or indifferent to their fate, and so their brother Muslims must help them.

Especially since the Serbs overran the mostly Muslim "safe haven" of Srebrenica two weeks ago, Muslim rulers and political figures have been talking of the war in religious terms, driven by popular sentiment in their countries to speak up for the Bosnian Muslims and pledge support, including money and weapons.

Some of Washington's best friends in the Muslim world, including Saudi Arabia, Jordan, Egypt and Turkey, along with the international Organization of the Islamic Conference (OIC), have begun urging action on behalf of Bosnia not because it is a member state of the United Nations under attack, as they viewed it in the past, but because the people being rounded up, driven from their homes, raped and murdered are Muslims.

Iranian Foreign Minister Ali Akbar Velayati said some OIC foreign ministers, including those of Egypt and Malaysia, pledged in a private meeting last week to give military assistance to the Bosnian Muslims, Reuter reported yesterday from Cyprus.

The Bosnian government never sought this turn of events. Bosnia has had a substantial Muslim population ever since many of its people adopted the faith of the Ottoman Turks, who seized control of the Balkans from the collapsing Byzantine empire in the 15th century. Contemporary Bosnians represented themselves as a secular, multi-ethnic European society, worthy of support because they represented the antithesis of religious extremes; the Bosnian Muslims were so secular, in fact, that they were viewed with suspicion by Muslims in other countries.

But with Western countries unable or unwilling to help them, the Bosnian Muslims are embracing whatever friends they can get, according to U.S. officials and diplomats from Muslim countries.

"You can sense the radicalization of the Bosnian government and of the people fighting, you sense their resentment," a North African diplomat said.

The Islamization of Bosnia and the war has disturbing implications for the United States for several reasons, U.S. officials and Muslim diplomats said. It undercuts the Clinton administration's efforts to reach out to the Islamic world and develop closer ties with Muslim societies. It raises the risk that Muslim countries could be driven to unite in support of the Bosnians, giving the Balkans war a religious cast reminiscent of bygone centuries. In countries such as Egypt, it plays into the hands of Islamic extremists, who are showing videotapes of Serb atrocities and telling people the situation in Bosnia proves the West is hostile to Islam. And it is obliging friendly Islamic states such as Egypt and Jordan to distance themselves a bit from the United States and its allies, which are portrayed by Muslim radicals as preventing the Bosnian Muslims from acquiring weapons to defend themselves.

"Everyone is focusing on the war's impact on Europe and NATO," a senior State Department official said, "but it's having a parallel effect in the Muslim world."

As Iran steps up its support, nations such as Turkey, Egypt and Jordan, whose troops are participating in the U.N. humanitarian force in what had been Yugoslavia as members of the international community, are under increasing pressure to openly back the Muslim-led Bosnian government because "they don't want to leave the Iranians to hold the moral high ground of Islam," this official said.

Egyptian Foreign Minister Amr Moussa said the Serbian assault on the Muslims of eastern Bosnia "is the responsibility of all Muslim countries," according to Cairo Radio. Egypt is planning to sponsor a U.N. resolution supported by most Islamic nations calling for an end to the embargo on arms shipments to Bosnia, an Egyptian diplomat said.

U.S. officials have identified Iran as a major supplier of arms to the Bosnian Muslims, in defiance of the U.N. embargo. Iranian officials have been describing the conflict as an anti-Muslim campaign and portraying their country as the defender of the faith. Iran has long had Revoluntary Guard cadres in Bosnia preaching Iran's brand of Islamic militancy.

"Bosnia is a bleeding limb of the body of Islam and the body of Islamic society," said Ayatollah Ahmad Jannati, the Iranian mullahs' spokesman on Bosnian affairs, in his Friday sermon after the fall of Srebrenica. "An Islamic town, which was supposed to be a safe area, has fallen. Other towns are under threat and the whole world is aware of this. . . . Why is the world silent on the plight of the Bosnian Muslims?"

Turkey, by law a secular state although its population is overwhelmingly Muslim, condemned the Serb assault on Srebrenica in a strong statement that never mentioned the victims' religion. But it is becoming increasingly difficult to filter the religious component out of Turkey's policy, a Turkish diplomat said.

"We have been telling our allies throughout the war that unless the international community does something about what is going on in Bosnia, the moderate governments in the Mideast will come increasingly under the pressure of fundamentalist forces. . . . It will be seen as a conflict between Christianity and Islam and fan anti-Western sentiments in the Islamic world," he said.

"We always said this war is not a religious thing, but a lot of people in the Muslim world think it is," an Arab diplomat here said. "A lot of people in the Islamic world share the view that if the shoe were on the other foot in Srebrenica, the outcome would have been different."

As if to confirm his comment, thousands of Muslims rallied in Bangladesh on Friday to protest what they called "genocide" of their co-religionists in Bosnia.

"There is a sense of outrage in the Muslim world," a Pakistani official said. "This is not World War II, where people had the excuse that they didn't know what was happening in those camps."

The Serb assault on Muslims "is a big boost to Islamist parties" in countries such as Egypt, said Khalid Duran, a Moroccan-born scholar who edits the magazine Trans-State Islam. "They are telling people, look, the Bosnians didn't want to be Muslims, they wanted to be Europeans, even communists, and still nobody in Europe accepts them. You have no choice but to be Muslims," allied in defense against a hostile West.

Since the fall of Srebrenica, Saudi Arabia and Jordan have announced they will send aid to the Bosnian Muslims. These contributions will supplement a steady flow of donations from individuals and from Muslim organizations in many countries, according to U.S. officials.

The Bosnian government "has plenty of money," an intelligence official said. In addition, according to U.S. and other sources, the Bosnian Muslims are receiving regular shipments of military equipment from at least four mostly Muslim countries: Iran, Malaysia, Pakistan and Turkey. Staff writer R. Jeffrey Smith contributed to this report. CAPTION: Bosnian refugee children from Srebrenica enclave take a lesson in the Koran in a makeshift tent mosque at the crowded U.N. air base camp in Tuzla.