D.C. Council Chairman Arrington Dixon declared his opposition yesterday to the most important elements of Mayor Marion Barry's long-range financial plan for the District of Columbia.

Dixon, who has been distancing himself from the mayor on city financial matters since the plan was released in July, said he opposes Barry's proposal to borrow $215 million this year to pay off accumulated debts, is against the mayor's proposal on where to seek the loan, and opposes the mayor's recommendation that $10 million a year be taken out of future operating budgets to repay deficits incurred in the past.

He proposed instead that the city defer borrowing until council members are satisfied that the money is needed, revise its budgetary and money-management procedures, and ask Congress for legislation that would allow the city to borrow as needed in the private market.

Once again accusing the mayor of failing to provide convincing figures to show that his proposals are necessary, 'dixon said that "The council and the public have been kept in the dark" about how much money is needed to keep the city solvent. "It would be unconscionable," he said, "for us to approve large amounts of borrowing to cover bills that are not yet due and may exist only on paper."

His comments were printed in a 30-page analysis of Barry's plan -- described in a accompanying news release as a "white paper" -- that was distributed to the press before it was given to other council members or to the mayor.

Barry did not receive his copy until late afternoon. A spokesman said that the mayor's plan was "very carefully developed over 60 days" and that the council was well briefed at the time. He said he was "surprised" that "today out of nowhere, without any warning, much less a briefing, Chairman Dixon tosses his surprise package on everybody's table." He said the mayor and his staff would comment later on the substance of Dixon's proposals.

Dixon's views were developed during four days of hearings on Barry's plan that the chairman held last month. His conclusions generally reflect the views of the witnesses at those sessions who questioned the legality and advisability of the plan, and did not come as a surprise to other city officials. The significance of Dixon's report lies less in financial specifics than in the politics of the developing struggle between Barry and Dixon over control over the District's financial future -- especially since some of his proposals, such as monthly reports to the council on the city's financial status, already have been enacted.

Dixon has sniped at the mayor over his management of the city's finances, his implementation of the new computerized accounting system, and his proposals to limit salary increases for city workers. Barry has suggested that Dixon is laying the groundwork for a challenge to him in the 1982 mayoral election.

Dixon has not been able to mobilize support for his views among other members of the council, but as chairman he does have some power to derail Barry's proposals by referring them to the Committee of the Whole, of which he is himself chairman, rather than to any other committee that might give them a better reception.

Private auditors hired by Congress to clean up the city's chaotic books have calulated the city's total cumulative deficit at about $409 million -- $284 million from past years another $125 million from the fiscal year that ended Sept. 30. They put the city's immediate cash need at $215 million and said repayment of the rest could be spread out over 20 years.

Barry proposed to raise the $215 million by borrowing from the Federal Financing Bank, a subsidiary of the U.S. Treasury that lends to U.S. government agencies or to borrowers whose notes are guaranteed by the government.

Dixon, recalling that witnesses at his hearing had questioned the figures, said, "I strongly recommend that the council not act on any specific borrowing legislation until the executive [Barry] submits a detailed list of cash obligations that comprise the deficit." If the $215 million is needed, he said, it should not be borrowed through the Financing Bank because it charges interest higher than the currentTreasury borrowing rate. Rates on private bond market are substantially lower.