A week after a powerful earthquake ravaged northwestern Turkey, a behind-the-scenes struggle is taking shape between the resolutely secular government and the country's powerful and well-organized Islamic movement.

The contest--partly a gathering war of words, partly a matter of power politics and muscle-flexing--involves the government's apparent unease over emergency relief programs mounted by Turkey's main Islamic-oriented political party and a host of Islamic humanitarian relief organizations.

Barraged by criticism because of its own slow, uncoordinated response to one of the greatest natural disasters in the country's history, the government has watched its Islamic-oriented opposition move into areas hit hardest by the quake with relatively quick and efficient relief operations--soup kitchens, mobile hospitals, food-distribution points, rescue teams and clean-up squads.

The government's fear, now being expressed explicitly, is that pro-Islamic politicians will be able to turn the quake, and the authorities' fumbling response to it, to their advantage. In Turkey, where a pro-Islamic government was forced from power just two years ago by the fiercely secular military, the unfolding of such a struggle has major implications for the country's political stability.

"It's the classic environment in which Islamists thrive because of their grass-roots organization, which is often so much better than the government's own," Alan Makovsky, Senior Fellow at the Washington Institute for Near East Policy, said in a telephone interview.

On Tuesday, the government froze the bank accounts of two disaster-relief agencies it regards as Islamic in character, insisting they had not complied with fund-raising regulations.

In at least one instance--in the quake-damaged town of Akyazi, about 100 miles east of Istanbul--government officials last week halted the work of a volunteer clean-up crew dispatched to the earthquake zone by the Istanbul branch of the Islamic-oriented Virtue Party, which finished third in April's nationwide parliamentary elections.

Some pro-Islamic politicians suggest the government fears losing ground in the aftermath of the quake, and some candid government officials agree. "The damage from the quake is enormous, and of course it's a common sociological trend that victimized people tend to move toward extreme ideological positions," said Erol Cakir, the governor of the Istanbul region.

As for the Virtue Party and other Islamic-oriented groups in Turkey, the governor was blunt. "I think they're trying to use [the earthquake] to further their own interests," he said.

The tension between secular and observant Turks is one of the main political schisms in the country, and one of the main sources of inflamed political passions in Turkey. Two years ago, the military-dominated National Security Council forced an Islamic-oriented government from power, fearing it was shifting Turkey away from its traditional secular, pro-Western leanings.

This spring, a religiously observant woman was prevented from taking a seat in parliament she had won because she wears a traditional Muslim scarf on her head, a sign of her devotion. There have also been large rallies by pro-Islamic students to protest the government's ban on such head scarves at state universities.

Now, the earthquake's rubble may become a new battleground in the ideological contest between secular and religious Turks. In the most damaged areas of the country, where thousands of apartment buildings have been reduced to rubble, there has been a massive private-sector response to the quake. But few non-government groups have the organizational prowess of the Islamic organizations, whose relief projects are widespread and varied.

In the quake-battered city of Sakarya, for instance, the Virtue Party has set up a large soup kitchen and food-distribution area in the playground of an elementary school. The other day, Fatma Bayram, a hollow-eyed woman left homeless by the Aug. 17 earthquake, tromped through the wreckage of the city for more than a day before she heard about the Virtue Party relief operation. When she went there, Virtue volunteers from Istanbul provided her with a large sack of rice, pasta, biscuits, salt and tea.

Bayram, a 35-year-old mother of three, was grateful, and in time her providers believe her gratitude will translate into political support. "We're not trying to promote our party; we're just trying to help people," said Ali Yeniyurt, a Virtue Party volunteer. "But of course these people are not stupid; they will change their minds when they see an organized political party in action."

That, in a nutshell, is precisely the government's concern. And it may be well-grounded. Throughout the earthquake zone, volunteers from cities controlled by the Virtue Party--including Istanbul and the capital, Ankara--have fanned out to provide an array of disaster-relief services. In Istanbul, the party linked municipal districts with towns in the earthquake zone in a sort of sister-city arrangement. Hundreds of party volunteers man warehouses, clean-up crews and soup kitchens in the quake area during the week; thousands came on the weekend.

Islamic-oriented humanitarian groups also have dispatched dozens of trucks carrying medicine and other supplies to the neediest towns and cities. The most prominent such group, the Istanbul-based Foundation for Human Rights and Humanitarian Relief, had provided aid to predominantly Muslim victims of the wars in Kosovo, Bosnia and Chechnya.

On Tuesday, it discovered that its three bank accounts--in dollars, German marks and Turkish lire--had been frozen by order of Cakir, the Istanbul governor. The next day, its offices were visited by police officers who recommended that the group drop any reference to a donation campaign from its newspaper ads.

Cakir, in an interview, said the group's bank account and that of another organization he regards as pro-Islamic, the Organization of Human Rights and Solidarity for Oppressed People, known in Turkish as Mazlumder, were blocked because they had failed to register their fund-raising campaigns with the government. He suggested that the groups could divert funds to purposes other than earthquake-relief in the absence of strict government oversight.

"All legal institutions may have some illegal connections," he said. "This might be the case here."

"If they don't like it," he added, "they can appeal in court."

The Virtue Party was formed last year from the ashes of a predecessor, the Islamic-oriented Welfare Party. Welfare had headed a coalition government for a little less than a year, tentatively advancing a moderately pro-Islamic agenda, until it was pushed from power by the military-dominated National Security Council in the spring of 1997. The party was then banned and its top leaders barred from politics, and the Virtue Party rose in their place, offering a similar pro-Islamic agenda and a platform for many, though not all, of the same activists.

The Islamic movement has lost some ground in parliament, but at the local level, the Virtue Party remains a powerhouse, controlling four of the largest cities in Turkey. As it happens, the party is also strong in a number of the cities most damaged in the quake, including Sakarya, also known as Adapazari, and Golcuk.

"People are suffering. Its a very harsh moment for Turkey, and very honestly, we are not providing aid to be noticed," said Murat Yalcintas, a Virtue Party member who holds a seat on the Istanbul city council.

"Whatever happens," he said, "the state is our state, and we're going to work together for the moment. But when this passes, the time will come to question the government's efforts. . . . We are challenging the system and saying it should be changed."

CAPTION: A Sakarya couple waits at a field hospital for treatment for their son's foot, injured in the quake.

CAPTION: Residents of the quake-damaged town of Sakarya wait in line for food provided by volunteers from Fatih, a largely Islamic suburb of Istanbul.