Presidential adviser Edwin Meese III indicated today that the administration is leaning toward two tough and intensely controversial anti-crime measures: preventive detention and an easing of rules set up to deter illegal police searches.

Meese said the law-and-order proposals were in the early stages of administration consideration and offered no specifics or commitments. But following a speech in which he called crime "the number one social problem," Meese made the administration's direction clear.

A preventive detention law exists only in the District of Columbia, where it is being challenged in the courts. A federal preventive detention law would allow judges to deny bail to defendants awaiting trial on federal charges who are considered dangerous.

"Under carefully limited conditions," Meese told reporters, "I think it is very desirable."

The second measure discussed by Meese would modify the "exclusionary rule," under which judges throw out illegally seized evidence -- often with the result of acquittal or reversal of a criminal conviction.

"There's a good basis" for modifying that rule as well, he told reporters. The exclusionary rule "hasn't worked out as ideally as some judges thought it would."

Meese said the administration has not "zeroed in" on specifics for either proposal. But on the exclusionary rule, law enforcement officials have been pushing for creation of a "good faith" exception that would allow use of tainted evidence if the constitutional violation by police or FBI was unintentional or unknowing.

An administration campaign on these issues appeared to be materializing throughout the American Bar Association convention meeting here this week and last week. Vice President Bush spoke critically of the exclusionary rule in a speech here Monday. Attorney General William French Smith singled out the rule and the concept of preventive detention when he spoke here about options under consideration by the administration.

Federal legislation in these areas would apply only to federal crimes. Traditionally, however, states and state courts have followed the federal lead.

Meese also endorsed the idea of donating unused military prisons around the country for use by state and local governments to ease their shortage of prison space. He said the secretary of defense has begun an inventory of such facilities.