Much of the $687 million Congress appropriated last year to fight drugs is failing to reach the nation's largest cities, the U.S. Conference of Mayors said yesterday.

In addition, said Kansas City, Mo., Mayor Richard Berkley, prospects for this year's battle, indicated by funding levels on Capitol Hill, are even bleaker.

Berkley, president of the mayors' group, made his comments in releasing a conference survey of how 42 of the nation's largest cities have fared since President Reagan signed the much-touted Antidrug Abuse Act of 1986 on Oct. 27, 1986.

"This survey suggests that America has lost its first battle in the war on drugs -- by default," Berkley told a news conference. The survey found that only $2,220,000 of the $687 million has been passed to the cities surveyed. Berkley largely blamed states for delays in getting money into the antidrug fight.

"Obviously, we are in favor of direct grants to our larger cities," he said.

The report said the law was passed "in the context of getting help to the cities, to the trenches in the war on drugs. What actually passed Congress was a bill which provides funds primarily to the states, with the requirement that a good portion be passed through to local jurisidictions."

Only Washington, which operates as a city and a state for federal funding purposes, had received any money, $800,000 for enforcement.