District officials this week defended the city's contracting practices in the face of congressional action to prohibit the city from handing out contracts on a noncompetitive basis, arguing that 92 to 95 percent of the contracts already are awarded by competitive bids.

But critics maintained that the District repeatedly has circumvented its own competitive bidding regulations and that its figures are misleading and disguise loose practices that enable millions of dollars' worth of contracts to be awarded without true competition.

"If it's 92 percent competitive District-wide, then give me your biggest hat and I'll eat the sucker," said Albert DeFazio, evaluator in charge of District government investigations conducted by the General Accounting Office, the investigating arm of Congress.

DeFazio agreed with city officials that the District has enough regulations requiring competitive bidding and placing strict limits on the kinds of contracts that can be negotiated with one firm. "They District officials just don't follow 'em," he said.

Interest has grown in both the House and Senate to put strict requirements on the District's contracting practices, a reaction to press reports detailing large contracts awarded without competitive bidding.

The House Appropriations Committee on Wednesday added a requirement to the District's fiscal 1986 budget, which must be approved by Congress, that would require that all District contracts be awarded by competitive bid.

"I think it's a good idea," said Sen. Arlen Specter (R-Pa.), chairman of the Senate Appropriations subcommittee on the District.

Specter, Rep. Julian C. Dixon (D-Calif.), chairman of the D.C. Appropriations subcommittee in the House, and Rep. Ralph Regula (R-Ohio), the sponsor of the amendment, said they do not want to do anything that would undermine the District's minority contracting program.

Under that program, 35 percent of the city's contracts are set aside for minority firms. City officials said there is competition within this so-called "sheltered" market but expressed concerns that a flat requirement for competitive bidding might prevent them from continuing such a program.

However, Specter and congressional staff members said the language of the amendment could be refined to make clear that a minority contracting program still would be allowed.

"I think they the majority of contracts are competitively bid. I don't know what the criticism is all about," said Brij M. Malhotra, material management administrator in the D.C. Department of Administrative Services, the city's chief purchasing agency.

William B. Johnson, director of the department, estimated on Wednesday that 92 to 95 percent of the city's contracts are competitively bid. Yesterday Johnson provided figures showing that his department awarded 496 contracts worth $96 million in fiscal 1984. Of those, 21 contracts for amounts over $25,000 each and totaling $3 million were awarded on a sole-source basis, equivalent to 4.2 percent of the total.

Johnson said he could not immediately say how many contracts under $25,000 were sole-source. His figures did not include millions of dollars worth of contracts awarded by the Departments of Public Works, Human Services and Housing.

The congressional action was prompted by reports in The Washington Times that the city had awarded a $20-million-a-year fuel contract on a noncompetitive basis to Tri-Continental Industries Inc., a company headed by a political supporter of Mayor Marion Barry.

City officials told Dixon that the contract was competitively bid but did not provide reporters with documents or information to substantiate the claim. Johnson referred inquiries on that contract to Herbert O. Reid Sr., the mayor's legal counsel, but Reid was not available.

The District pays substantially more for fuel than surrounding jurisdictions because it purchases fuel directly from Tri-Continental, a minority-owned firm, rather than through a purchasing program set up by the Metropolitan Washington Council of Governments 10 years ago for 16 area jurisdictions.

The District loses more than $4.4 million a year by failing to participate in the cooperative purchasing program, according to a comparison of the unit cost of fuel paid by the District and COG in 1984.

D.C. City Council Member Betty Ann Kane (D-At Large) has introduced bills to permit D.C. to join the cooperative purchasing program. Kane said she believes the legislation was stalled by opposition from the mayor.