The Justice Department charged yesterday that the Austin, Tex., school system's policy of sending children to neighborhood schools has been used deliberately to segregate black and Maxican-American students from white students.

In a brief file in the Fifth U.S. Circuit Court of Appeals, the department asked that the federal courts order "an appropriate desegregation plan." The brief did not specify what form the plan should take. However, those involved in the case agspe that any significant change in the racial balance of Austin school would require extensive busing of purpils throughtout the city.

The government's action marked the latest turn in a case that has been bouncing up and down in the federal courts since 1970.

Last May, the fifth circuit appellate court ruled that Austin's neighborhood school policy, when considered against a background of residential segregation, amounted to unconstitutional discrimination. The court ordered a crosstown busing plan that would have involved as many as 25,000 students.

But, on Dec. 6, the Supreme Court nullified the busing decree and sent the case back to the fifth circuit for reconsideration. The Supreme Court directed that the case be looked at again in light of recent decisions upholding laws and official actions that are discriminatory in their effect but that have not been shown to be discriminatory in their purpose.

Austin school officials have contended that they are running a racially neutral system and that any racial imbalance in specific schools in not intentional but was the coincidental result of other factors such as housing patterns.

However, the Justice Department, in its current brief, argues that Austin officials "have failed to carry the burden of proving that they acted in a racially neutral manner." The brief cites extensive evidence to back up its contention that Austin used such devices as the drawing of school district lines and the location of new school construction to segregate minority students deliberately.