The District of Columbia government paid its bills more slowly than all but one of 20 federally connected agencies checked last year, the General Accounting Office reported to Congress this week.

The finding was based upon checks prepared for payment of assorted city bills on a single day, April 2, 1976, Comer S. Coppie, the city's budget director, said that the city has improved its procedures since that date and that another check should put the District in a better light.

The city's ranking was determined after GAO personnel visited 58 centers where federal payments to creditors are processed by various agencies. These included one center operated by the District, which is not a federal agency but uses federal procedures and the U.S. Treasury in paying creditors.

Sen. Robert Packwood (R-Ore.) said he arranged the hearing after complaints from constituents that federal small businessmen often are squeezed agencies are so slow to pay bills that to meet payrolls and other commitments.

Results of the check of agencies were disclosed to the Senate Small Business Subcommittee by Donald L. Scantlebury, director of the GAO financial and general management studies division.

The District was listed by Scantlebury on a tabulation of agencies, but he did not discuss the city specifically in his testimony.

The GAO check showed that, 29 per cent of all bills presented to federal agencies at the 58 payment centers were paid more than 30 days after creditors submitted invoices for goods or services.

Based on the one-day spot check, the city paid 72.3 per cent of its bills more than 30 days after invoicing. Those bills represented about $28,000 of the $52,000 in payments made on the day of the check. For the most part, late payment was caused within city agencies that received the goods or services, and not in the budget office that certified payments, the GAO reported.

Only the General Services Administration, with a 73.8 per cent figure, ranked lower than the District.

The best record was that of the Justice Department, which paid only 3 of 46 invoices, or 6.5 per cent, more than 30 days after invoicing.

Scantlebury said the city's record apparently is symptomatic of problems uncovered last fall by Arthur Andersen & Co., an accounting firm for the Senate District Committee. As a result of the Andersen report, the city's account structure is being revamped.

Coppie said improvements now enable his office to process bills and certify them to the city treasurer's office in an average of five days. The treasurer's office prepares the checks.

Coppie said the city payments to utility firms, publicized two years ago have been resolved.