ZAGREB -- The United States and Russia will employ a mix of inducements and threats to push the Bosnian Serbs into joining a budding Croat-Moslem federation in Bosnia or ceding to it conquered land, diplomats say.


Incentives to board the superpower peace train in the Balkans, they say, would include the right to keep some land taken in battle and revocation of U.N. sanctions imposed for aggression.


If Serbs keep the 70 percent of Bosnia they hold and firght for more, a U.N. arms embargo could be partially lifted to exempt Croats and Moslems.


Western diplomats sketched the next stage in Bosnia's peace process following a U.S.-brokered Croat-Moslem deal to set up a decentralized cantonal state with a joint army, ending a bloody scramble for ethnically mixed territory.


Russian peace envoy Vitaly Churkin began shuttle diplomacy this week to usher the Serbs, linked to Russia by Slav heritage and Orthodox religion, into the U.S.-sponsored peace plan to forge a durable, overall settlement.


The Serbs have hinted at marginal territorial concessions but nothing close to the 20-30 percent demanded by Croat and Moslem leaders keen to repatriate refugees and create an economically viable state with defensible borders.


"The plan now is to go to the Croats and Moslems, ask them what their territorial bottom line is and then go to the Serbs and get them to negotiate with a mixture of inducements and threats," a senior Western diplomat said.


"You say to the Serbs, 'You already have 70 percent. In return for recognition of some of your gains you need to give the Moslems and Croats some good quality territory.'


"If the Serbs do not play ball, they run into the possibility of renewed efforts to lift the arms embargo."


The world would also ensure that ethnically cleansed territory would be placed in indefinite quarantine.


"We'd devise a way of 'poisoning' property acquired by ethnic cleansing," a diplomat said. "We'd say the day Serbia wants to reenter Europe, all property claims would be revived, and no World Bank or International Monetary Fund money paid where claims are unresolved or the environment is unsafe for refugees to return."


Diplomats said satisfying the Bosnian government demand for the return of most if not all territory "ethnically cleansed" of Moslems in north and east Bosnia would be impossible.


A compromise might be to assign Serb-blockaded Moslem enclaves in Bosnia to the federation with a connecting territorial corridor, diplomats said.


"The trick is to persuade the Serbs it's in their interest to accept a settlement that gives them a fairly large part of the loaf they were after," a diplomat said.