KIEV, U.S.S.R., AUG. 27 -- Less than a week after applauding Boris Yeltsin for his lead role in smashing a hard-line Kremlin coup, politicians here in the Ukraine were criticizing the Russian president for raising doubts about Ukrainian independence by calling for border negotiations with republics seeking to leave the Soviet Union.

Yeltsin's spokesman said Monday that this referred principally to regions of the eastern Ukraine and northern Kazakhstan heavily populated by Russians, spreading fears here that Russia would seek to annex large areas of the Ukraine.

"This statement created a loud echo everywhere in the Ukraine, other republics and even abroad," Ukrainian legislative chairman Leonid Kravchuk said today. Kravchuk, a long-time Communist ideologue -- who also announced that he had quit the party -- described any territorial challenge by Russia as "very dangerous" and vowed to oppose efforts by Yeltsin and Soviet President Mikhail Gorbachev to steer the Ukraine toward membership in a new Soviet federation.

Ivan Drach, chairman of the powerful Ukrainian independence movement Rukh, was far harsher in his criticism of Yeltsin's statement, saying: "The new government of Russia has the 'Big Brother' syndrome and wants to prevent the Ukraine from gaining independence." Officials in Kazakhstan expressed similar outrage at the prospect of ceding territory to the Russian republic.

Gorbachev, meanwhile, apparently sought to defuse the issue, saying today as he left the Soviet legislature: "I think you are misinterpreting this. It's clear that we are not going to review borders."

Still, just three days after the Ukrainian parliament voted overwhelmingly to declare independence, legislators of all political stripes acknowledged that their bid to leave the Soviet Union could lead to a potentially explosive struggle with Russia and the Soviet military. "{The declaration} doesn't mean that the job is finished," said Sergei Odarich, deputy chairman of the Rukh executive commitee. "Quite the opposite; the serious work must now begin."

Although the Baltic republics seem to have passed an informal threshold of independence and will be allowed to go their own way, the Ukraine is in a far trickier position. With more than 50 million people -- a fifth of them Russians -- it is larger than all of the republics except Russia. It is a resource-rich industrial powerhouse and the country's agricultural heartland. Moreover, Ukrainian politicians say, it is host to vast numbers of Soviet troops and a weapons arsenal that includes nuclear weapons.

The Ukrainian independence declaration asserted that the republic would assume control of military units on its territory, and Kravchuk said today he will appoint a defense minister to begin talks with the Soviet military on the fate of the armed forces here -- estimated at more than 1 million.

"The military formations in the Ukraine are an enormous force," Kravchuk said, in apparent warning to radical nationalists urging a fast-track approach to independence. "Any haste in resolving this question may entail very dangerous action, so we have to consult with the military."

Kravchuk evaded questions about nuclear weapons, while Rukh and the largest reform party in the Ukrainian parliament -- Democratic Revival of the Ukraine -- are calling for the republics in which Soviet nuclear weapons are stationed to sign a treaty agreeing that the weapons could be used only with the approval of all signatories. "There shouldn't be only one person who can push the button," said Rukh official Odarich.

Most Ukrainian politicians -- both Communist and opposition -- were caught off-guard by the coup and its sharp anti-Communist backlash and are trying to catch up with events. After adopting a relatively cooperative position on union membership before the coup, they now oppose joining a looser Soviet federation being proposed by Yeltsin and Gorbachev, opting instead for full sovereignty and confederation with former Soviet republics on economic and military affairs.

But politicians here concede that real independence can come only in carefully prepared stages. On Dec. 1, the parliament's declaration is to be voted on in a republic-wide referendum that is expected to endorse independence by a large majority. On the same day, voters are to elect -- for the first time -- a Ukrainian president with strong executive powers.

In succeeding months, reformist legislators want fresh parliamentary elections aimed at marginalization of the Communist Party, which currently holds a majority in parliament. Rukh charges that a quarter of the Communist legislators backed the abortive coup. It has accused Kravchuk, a potential presidential candidate, of a shadowy role in the takeover crisis.

But the greatest stumbling block to peaceful independence could be conflict with Russia over territorial issues, particularly as regards the Crimea and the industrialized Donbass region, where Russians are heavily in the majority. Democratic Revival member Valery Khmelko expressed great concern that any Russian attempts to gain control of those areas -- even by diplomatic means -- could trigger the kind of nationalistic passions that are turning Yugoslavia into an ethnic battlefield.