An internal police investigation of Operation Caribbean Cruise has found that police involved in the failed exercise violated fundamental procedures for dealing with confidential informants and that some officers used police funds for private purposes, according to sources familiar with the probe.

The Caribbean Cruise operational handbook, given to some police involved in the exercise, was outdated and inaccurate, and information contained in a 250-page police affidavit in support of search warrants was "not true and not correct," a police official said.

In addition, a group of black police officials has written a terse letter to Deputy Chief James P. Shugart, commander of the department's 4th District, blasting "the apartheid policy of the 4th District" and the "categorical and systematic exclusion of any black officer, sergeant or lieutenant from the planning, directing or policy-making positions of the ill-fated Caribbean Cruise operation."

The letter, which a source in the 4th District said was written by 13 of the unit's 14 black police officials, expressed their "considerable disgust and indignation relative to the contemptuous policy of insidious racism and the misguided practice of cronyism which has been permitted to become the standard operating policy of the 4th District."

Police have said that Caribbean Cruise, the largest police operation in the city's history with 69 homes simultaneously raided in a search for drugs and weapons, failed because word of the early-morning raids apparently leaked out to the suspects.

The Feb. 22 offensive, which involved more than 500 police officers, was designed to crack what police called a heavily armed drug network in Northeast and Northwest Washington involving Rastafarians, members of a Jamaican religious sect.

Although police expected to arrest as many as 200 persons and seize huge caches of drugs and automatic weapons, only 27 persons were arrested and $20,000 in drugs and 13 weapons, none automatic, were confiscated.

After the raids, local Rastafarians bitterly complained to Mayor Marion Barry and D.C. Police Chief Maurice T. Turner Jr. that the police operation was an unwarranted attack on their religion. Members of the local Caribbean community were particularly upset about some statements in the operation handbook, including a claim that Rastafarians were distributing drugs "to generate funds . . . for the violent overthrow of the present Jamaican government."

According to Dera Tompkins, a coordinator for the Coalition Against Operation Caribbean Cruise, Turner has written a letter acknowledging that some of the statements were inaccurate and insensitive. Turner has declined to comment on the matter.

The probe was launched to find out why the exercise had failed. On Wednesday, Barry said that concerning possible leaks "we know enough about what happened." He declined to elaborate on this or any other aspect of the investigation's findings. However, a police source familiar with the Internal Affairs Division investigation said, "a couple thousand dollars" in confidential funds used to pay informants was used by investigators for their own purposes, such as buying food and drink during the 16-month investigation.

This official and another police source familiar with the investigation also said that investigators gathering information for a police affidavit supporting the search warrants executed in the raid violated procedures by not searching police informants after they had bought drugs from suspects.

When an informant buys drugs, according to one of the sources, "he should come back to the control officer, who searches him and takes the drugs and documents the time and date and location." Because this wasn't done in some instances, the source said, the police affidavit was "not true and not correct."