Congress and the White House reached agreement yesterday on new conditions for conducting most mandatory drug tests of federal workers that will delay the implementation of tests for at least two more months.

The delay will give the administration time to develop uniform plans for testing employes in sensitive positions for the same drugs under the same conditions, and for the public to comment.

Previously, individual agencies The administration reacted with "benign neglect."

had wide latitude to test employes for different substances.

Rep. Steny H. Hoyer (D-Md.), author of a House provision to ban the use of federal funds for drug testing, backed off yesterday as a House-Senate conference committee agreed on a nearly $10 billion supplemental appropriations bill.

"I believe we reached a compromise that if we go ahead with testing -- as the Senate made clear we were going to -- we have established a framework for protecting employe rights and the accuracy of the tests to the extent possible," he said.

Hoyer said he doubts that the agreement would actually delay the tests because most agencies are far from ready to begin. The Justice Department, however, was close to announcing who was going to be tested two weeks ago. The Transportation Department, which plans to implement tests this summer, was exempted by the conferees.

The Reagan administration won last-minute language in the usual statement accompanying the conference report emphasizing that the new conditions were not designed to trigger endless legal challenges on procedural grounds.

However, administration efforts to add language barring judicial review on procedural grounds failed to win support.

One official present at the conference said the administration reacted to the final drug agreement with "benign neglect."

James C. Miller III, director of the Office of Management and Budget, who has handled negotiations on the issue, was traveling in Colorado yesterday and could not be reached for comment.

The compromise calls for the administration to issue mandatory guidelines requiring:That the best available technology be used to test urine samples. That the Department of Health and Human Service specify which drugs will be included in the tests.

In addition, HHS must inform Congress of the criteria used in selecting workers to be tested and how the tests will be conducted. OMB must analyze the costs.

In addition to the Transportation Department, the agreement exempts areas in which testing was already being conducted last September when President Reagan signed his executive order requiring a "drug-free workplace." These are principally in the military.

Hoyer and Sen. Barbara A. Mikulski (D-Md.) had argued with the administration over drug-testing language for several weeks.

Mikulski said yesterday that the final language "strikes a compromise between the need for a drug-free workplace and the rights of federal workers, including the right to laboratory accuracy."

"The final product does not contain every provision I or my colleague from Maryland wanted, nor does it contain every nuance the administration wanted," she said. "Perhaps our mutual dissatisfaction over portions are the best measure of a reasonable compromise."

Hoyer, who said he believes that random testing without probable cause is unconstitutional, fought to force the administration to issue regulations instead of the more informal guidelines in existence. Guidelines are typically advisory and take effect immediately without a period for public review and comment.

The administration objected that regulations would delay testing indefinitely and open up the effort to new legal attack on procedural grounds.

In the end, Hoyer agreed to mandatory guidelines with a 60-day comment period.