The already-complex legal battle surrounding the sale of the Source Telecomputing Co. to Reader's Digest has been further complicated by government claims to some of the company's assets and the freezing of its bank accounts.

Two banks have frozen the company's operating accounts, and the federal government has told the company it intends to recover money owed on a defaulted government-guaranteed loan following the announcement of the $3 million sale of STC's home computer service to the Reader's Digest Association Inc.

The two developments cloud an already-complicated legal battle over who owns The Source, a home computer information network that has been hailed as a major development with as much potential impact as the development of television or the telephone.

On Sept. 23, STC Chairman Jack Taub sold 51 percent of the stock of STC to the Reader's Digest Association, but two days later that sale was challenged in court. Former Taub associate William Von Meister was granted a court order temporarily barring Taub from selling or disposing of any additional shares of Source Telecomputing and forbidding Taub from making use of the sales proceeds without the court's permission.

"The court cannot stop the sale itself," but the court could declare the sale null and void, said U.S. District Court Judge Richard B. Kelam at the hearing on the request for a temporary restraining order.

Kellam has been hearing testimony in a lengthy legal dispute between Von Meister and Taub over who owns 31.4 percent of the stock in Digital Broadcasting, the original company that began marketing The Source. Taub removed the Source from DBC and set up Source Telecomputing as a totally separate company, he said.

Since the restraining order, minority shareholders in Digital Broadcasting Corp. other than Von Meister have notified banks where Source Telecomputing has accounts of their claim of $3.2 million against the assets of Source Telecomputing. The banks reacted by asking the courts to compel Taub and the minority shareholders to settle that issue. In the meantime, the accounts -- representing approximately $500,000 in the Bank of Virginia and less in the First American -- have been frozen.

The claim for $3.2 million is the same amount in which the federal government has an interest. DBC, which has been financially shaky for some time, had defaulted on a federally guaranteed loan. The North Carolina National Bank had lent DBC $6 million, of which 90 percent was guaranteed by the Department of Commerce Economic Development Administration.

According to papers filed in court in Fairfax County, when the loan was restructured in August 1979 the bank acquired a security interest in The Source. In July, the bank assigned its rights to the Economic Development Administration which wrote everyone connected with The Source to say that not only is the $3.2 million due, but also that $1,047.75 a day in interest was being added to the debt.

The EDA reiterated its claim of a security interest in The Source two weeks after the Reader's Digest sale.

When the EDA learned of the sale and the infusion of cash into the corporation, it noted "an obvious government interest in that," according to John E. Kennenhan of the EDA chief counsel's office.

A spokesman for Source Telecomputing said that the company is managing to operate in spite of the problems with its bank accounts but declined further comment on the array of legal problems facing the company. A spokesman for Reader's Digest also declined comment except to say that the company considered the sale a fait accompli .

The Source is a relatively inexpensive home computer network that offers customers such services as the United Press International newswire; quotes from stock and commodity exchanges; electronic mail; ready-made programs for accounting, word-processing and personal finance tasks; restaurant reviews; and electronic games.