A federal judge yesterday ordered a Northern Virginia businessman to appear before a grand jury in Alexandria that is investigating corruption in the General Services Administration.

District Judge Albert V. Bryan Jr. directed Peter C. Lous, a former employe of Computer Sciences Crop., to appear Oct. 18 before the jury and bring with him records of a data processing firm.

Lous has been told he is a "target" of the Alexandria GSA probe, according to a letter his lawyer filed in connection with the case.

The jury is investigating allegations that Loux received kickbacks from Icarus Corp., a Rockville computer firm, that sought subcontracts of GSA work from Computer Sciences.

The kickbacks allegedly were funneled through an intermediary computer concern and an array of bank accouunts, according to sources. The president of an intermediary firm has been granted immunity from prosecution in return for his testimony on the alleged scheme, the sources said.

Barnet Skolnik, Loux's lawyer, said yesterday he knew nothing about such allegations and declined further comment.

Earlier in the day Skolnik appeared before Bryan in Alexandria on a Justice Department motion to have Loux held in contempt for failing to appear before the jury. Skolnik said his client had ignored the jury's subpoena on his advice -- a decision Skolnik said was based on his "naive assumptions."

A Justice Department task force has been investigating a GSA contract with Computer Sciences since late last year. Under the contract the giant computer firm has received more than $100 million in federal funds.

Under the contract, the computer firm based in El Segundo, Calif., provided the government with a system for storing and retrieving computerized data at terminals in 7,500 government offices.

GSA auditors subsequently determined that GSA had overpaid Computer Sciences by more than $300,000 because the qualifications of some of its consultants, including some employed by Icarus, had been falsified to Lace them in higher pay brackets.

Computer Sciences has denied any kickbacks were involved. Herbert Blecker, president of Icarus, has failed to return a reporter's telephone calls.