RUSSIA, the Ukraine, and Byelorussia say their new commonwealth is open to all of the former Soviet republics, but some Central Asian officials fear their impoverished region will be left out of the new political arrangement.The development of a commonwealth could prompt the formation of a Central Asian union, posing a threat to ethnic Slavs living in the region, as well as opening up the possibility of the spread of Islamic fundamentalism in the republics, political observers say. The Soviet Central Asian republics - Kirghizia, Tadzhikistan, Turkmenia, and Uzbekistan - have been slow to react officially to Sunday's formation of the Commonwealth of Independent States. Uzbek President Islam Karimov, for example, said the new commonwealth "posed certain problems" but added more time was needed to analyze the developments, the Tass news agency said. Only Kirghiz President Askar Akayev, considered the most progressive leader in the region, has indicated he supports the initiative of the three Slavic republics, according to the Interfax news agency. The other leaders may be waiting to express their opinions until a winner appears in the political battle now raging in Moscow between Soviet President Mikhail Gorbachev and the leaders of the three Slavic republics, said Serozhdin Nastredinov, Tadzhikistan's permanent representative in the Soviet capital. Despite the hesitation, Central Asia is still controlled largely by conservative Communists, and there appears to be widespread support for Mr. Gorbachev's plan to revamp the nation into a confederation. Gorbachev is opposing the formation of the commonwealth, saying the leaders of the three Slavic republics - Boris Yeltsin of Russia, Leonid Kravchuk of the Ukraine, and Stanislav Shushkevich of Byelorussia - don't have the right to decide the future of the entire former Soviet Union. There could be serious consequences for Central Asia if the Slavic commonwealth becomes reality, said Turkmen Foreign Ministry official Sapar Anameridev. "There's always been a certain negative attitude on the part of the Slavs toward Central Asia," said Mr. Anameridev, speaking in a telephone interview from Ashkhabad, the Turkmen capital. "Now their true intentions are coming to the forefront." The Tadzhik and Turkmen leaders, along with the president of the Muslim-populated Caucasus republic of Azerbaijan, joined Gorbachev's opposition to the new commonwealth in a meeting on Monday. Nursultan Nazarbayev, the president of Kazakhstan also opposes the plan. The republic is 40 percent populated by Muslim Kazakhs, although Russians, Ukrainians, and others make up a majority. Some officials in the Slavic republics view Central Asia as a drain on their republics' resources. Central Asia is primarily agrarian, has little industry, and depends on subsidies from the Slavic republics. Byelorussian parliament chairman Shushkevich and others have said the Slavic commonwealth doesn't seek to leave other republics behind. But Shushkevich also told the Pravda newspaper that a similarly conceived Central Asian union may appear. Though a Central Asian political union appears to run against the wishes of regional leaders, they will unite if necessary, Anameridev said. "If they [the Slavs] abandon us we'll have no other option," he added. A Central Asian union would probably be conservative and Islamic in nature, effectively squashing any attempts at democratizing society and introducing a market economy in the region, some political observers say. Kirghizia, the most progressive Central Asian republic, stands to lose the most, said Valery Sandler, an editor of the Literaturnii Kirghistan journal. Under Akayev, the republic has been pursuing market-oriented reforms closer to those favored by Russia. Knowing it would benefit the republic's economy, President Akayev is pushing for Kirghiz membership in the Slavic commonwealth, but the mood of republican residents may block his plans, Mr. Sandler said. "In Kirghizia there is not as strong a belief in Islam as in Tadzhikistan, Turkmenia, and Uzbekistan, but the people here nevertheless feel closer to Islamic customs than to European culture," said Sandler. Meanwhile, some Russian ultra-nationalists, such as Vladimir Zhirinovsky, leader of the Liberal-Democratic Party of Russia, have denounced the formation of the Slavic commonwealth, saying it would allow Islamic fundamentalism to sweep across Central Asia. After years of religious isolation under the Communists, the Central Asian republics have recently been strengthening ties with Islamic states such as Iran and Turkey. Iranian Foreign Minister Ali Akbar Velayati toured the region late last month. But closer relations with the Islamic world will not necessarily lead to the development of a fundamentalist Central Asian Union, said Mr. Nastredinov, the Tadzhik official. Even if a moderate Islamic union emerged, however, it would have serious ramifications for the sizable Slavic population in Central Asia. According to Sandler, the formation of a Central Asian union would raise ethnic tension to dangerous levels. Russians and other Slavic nationalities are widely resented for not attempting to assimilate, he said. Anti-Slavic attitudes in Central Asia have already prompted Russians, Ukrainians, and other non-Asians to leave the region in recent years, and that trend would greatly accelerate with the formation of a Central Asian union. "There will be a threat to Russians, but in many ways they only brought it upon themselves because of their colonial attitudes," Sandler said. Ethnic tension would place Kazakhstan, whose northern half is Russian-populated, in an especially tricky position. Kazakh President Nazarbayev spoke in somewhat bitter terms about the commonwealth plans after his three-way meeting on Monday with Gorbachev and Mr. Yeltsin. In the end, the formation of the Slavic commonwealth may set off a chain of events that harms Russia, the Ukraine, and Byelo-russia more than it helps them, said Alexander Domrin, a mem-ber of the Russian parliament. A united Central Asia with strong ties to Islamic nations such as Iran, Pakistan, and Saudi Arabia could pose a large security threat to Russia, becoming a larger drain on resources than the region currently is. "By gaining something over the short term we are risking success in the long run," said Mr. Domrin. "We could have a jihad on our hands."