D.C. Police Chief Maurice J. Cullinane yesterday characterized as "stupid" a statement by Montgomery County Police Chief Robert J. diGrazia that the way to deal with hostage situations is to promise anything but give nothing.

"If you're going to keep any credibility for the future, then you've got to keep your promises," Cullinane said in an interview."If we destroy the fact that we do what we say we'll do, then you're putting a terrible burden on law enforcement all over the country."

Cullinane said his remarks were prompted by diGrazia's criticism of the way D.C. police handled last week's hostage-taking in the city. Twelve Hanafi Muslims held 124 persons prisoner for extended periods at three locations.

Maurice Williams, 24, a reporter for radio station WHUR, was killed during the siege at the District Building and several other persons were injured, including D.C. City Councilman Marion Barry. Others were injured at B'nal B'rith headquarters at 17th Street and Rhodes Island Avenue NW. None was hurt at Washington's Islamic mosque, the third site taken over by the Hanafis, on Massachusetts Avenue NW.

Part of the agreement negotiated by D.C. police to end the sieges was that the Hanafi leader, Hamaas Abdul Khaalis, be permitted to go free on his personal bond pending possible grand jury action. This prompted the following statement by diGrazia to The Washington Star.

"I don't know what the situation was. I wasn't there. It's difficult to second-guess these things, but my feeling is that if we're going to short-stop this sort of stuff, we've got to be tougher. Promise them anything to get the hostages out of there and after they're out, don't give them (the hostage-takers) Arpege."

A spokesman for diGrazia told The Washington Post last night that the statement represented the chief's views. The spokesman said di Grazia would have no further comment.

Cullinane said it "makes no sense" for officials who were not on the scene to make such statements. He said that maintaining credibility was crucial to dealing with any hostage situation and that diGrazia had served notice, in effect, that he could not be taken at his word.

Others who have been critical of the decision to release Khaalis include Senate Majority Leader Robert Byrd (D-W. Va.) and Sen. Lloyd Bentsen (D-Tex.). Cullinane said he regarded their remarks as "political," whereas diGrazia's was a "cheap shot" from a fellow police official.

Cullinane's views on the importance of "credibility" are shared by psychiatrists and other experts in the field. Some are known to have been highly critical in private of the decision of Indianapolis authorities to arrest Anthony G. Kiritsis moments after he had released Richard Hall. Kiritsis had wired a shotgun to Hall's neck after taking him hostage. Authorities had promised they would not arrest him if Hall were freed.

The negotiations that ended the Hanafi siege after 38 hours were conducted at B'nai B'rith headquarters with the help of the ambassadors of Iran, Egypt and Pakistan. Chief Judge Harold H. Green of D.C. Superior Court ordered the participants, including Khaalis, not to discuss what went on during the final meetings.

However, it is known that police felt the turning point came when Khaalis left his stronghold on the eighth floor of the B'nai B'rith building, thereby placing himself within reach of police and making it clear that he would not kill his prisoners.

He was persuaded to leave the eighth floor by Deputy Chief Robert L. Rabe, the department's negotiator in these situations. Cullinane himself persuaded Khaalis to surrender his weapons. The ambassadors -- all of them Moslem -- then appealed to Khaalis' sense of humanity to release the hostages.

Khaalis stated repeatedly that he had launched the action because of what he regarded as the unjust sentences meted out to six men convicted of murdering seven Hanafis at their headquarters at 7700 16th St. NW in 1973. One of his unmet demands was that the slayers be turned over to him.