A federal judge ordered the Department of Health, Education and Welfare yesterday to speed up college desegregation in six states, but he warned that the process must preserve the status of their historically black colleges.

Judge John H. Pratt directed HEW Secretary Joseph A. Califano Jr. to develop desegregation guidelines and transmit them to the six states and the courts within 90 days.

In developing the guidelines, "it is the responsibility of HEW to devise criteria for higher education desegregation plans which will take into account the unique importance of black colleges . . .," the judge declared.

In essence, Pratt shortened by 60 days Califano's request for 150 days to serve final desegregation guidelines on Virginia, Arkansas, Florida, Georgia, North Carolina and Oklahoma.

On March 22, Califano requested the additional time, in order to "consider carefully and fully the far reaching social and educational ramifications raised by this case."

In a letter to the court released by Pratt yesterday, a group of black colleges and their supporters suggested a number of guidelines aimed at preserving the integrity of black colleges in the desegregation process.

The group, called the National Association for Equal Opportunity in Higher Education, called for pressures on predominantly white colleges to increase their proportions of black students and faculty members.

But when applied to black colleges, the association said, the desegregation plans "should place no further burdens on them by requiring arbitrary quotas of white students or staff or by requiring other means of racial balance."

Desegregation plans should recognize black colleges as already in compliance with Title VI of the 1964 Civil Rights Act, the association said. The lawsuit that triggered Pratt's order was brought by the NAACP's Legal Defense Fund, charging the states with violating Title VI.

The black colleges expressed concern that any desegregation plan "focus on the educational needs of blacks, rather than on mechanical numerical schemes which do not take into account the end results to be accomplished."

They said the goal of any desegregation plan must be to increase educational opportunities for blacks, and they argued that black colleges are essential to achieving that goal. More than half the bachelor's degrees awarded to blacks each year come from black colleges, they said, and 80 per cent of the 1973-74 black graduates in the South earned their degrees at black colleges.

"We don't want states or judges making rulings that by such and such a date 45 or 50 per cent of the enrollment in black colleges has to be white, because those whites would be taking the place of blacks," said Elias Blake Jr., president of the Institute for Services to Education, which monitors opportunities for blacks in higher education.

Not only is it essential to preserve the black colleges, the letter to Pratt argued; in fact, states should adopt compensatory measures to make up for past discrimination.

"Budgetary support for the historically black institutions at something like 120 per cent of the formula provided to the other institutions is what we have in mind," the letter said.

Additionally, the black colleges said, when a state establishes new academic programs, they should be set up on black campuses first.

Pratt's order and the letter from the black colleges come at a time of mounting discussion and activity over the role and identity of black colleges.

Last Sunday, students at the black Virginia State College in Petersburg demonstrated in favor of preserving the school's black identity. For years Virginia governors have resisted federal integration efforts, in part on grounds that the identity of the black colleges would be jeopardized.

At a meeting of black educators in Washington this week, complaints by whites of reverse discrimination and preferential treatment were cited repeatedly as arguments in support of black colleges.

"In higher education, we all know the pendulum has swung back and the gains made by blacks and other minorities in predominantly white colleges and universities are diminishing, and the special efforts to increase minority participation in colleges, graduate and professional schools are under attack in the courts, faculty lounges, legislatures and private social settings," declared Bernard C. Watson, vice president for academic administration at Temple University in Philadelphia.

In New York, the Legal Defense Fund issued a statement promising to "continue to monitor HEW's performance to assure that HEW makes good its promises of civil rights law enforcement and does not return to the benign neglect philosophy which brought on this lawsuit in the first place." The case has been in various stages of litigation since 1970.