The presence of more uniformed police officers during the Republican National Convention led to a drop in the city’s crime rate last week, with the number of murders, rapes, and burglaries declining the most, city and police officials said yesterday.

“Crime in the last week is down 6% over what it was the same week a year ago, which is quite amazing,” Mayor Bloomberg told reporters in Brooklyn yesterday.

Mr. Bloomberg took his figures from Compstat, a police data system that showed a citywide drop of 5.9% in the seven major crime categories during the week that ended September 5. These categories include murder, rape, robbery, felonious assault, burglary, grand larceny, and grand larceny auto.

Murder dropped 40% during convention week to nine homicides, compared to 15 during the same period last year. In addition, rape fell 25% to 39 from 52, and burglary decreased 24% to 481 from 636.

Last week, about 10,000 police officers were deployed to provide security for the convention. Many of the officers were pulled from the outer boroughs to provide security around Madison Square Garden and other sensitive sites, and to be on hand for various protest marches in Manhattan. Police also worked overtime to prevent a shortfall in manpower.

The deputy commissioner for public information, Paul Browne, said the increased presence of police throughout the city helped to deter crime. “By putting the department on 12-hour tours during the convention, we were able to meet or exceed staffing in the rest of the boroughs,” Mr. Browne said.

The police borough of Manhattan South, where Madison Square Garden is located, experienced a 20.5% drop in crime, a greater reduction than any other borough. Staten Island was the only borough to show a significant increase in crime, by 11.5%.

In other Compstat categories, robbery slipped 1.2% to 479 from 485, and grand larceny auto dropped 14.2% to 444 from 518. However, the categories of felony assault jumped 10.6% to 404 from 365, and grand larceny rose 4.4% to 946 from 906.The city experienced a 15.3% decline in shooting incidents, to 33 from 39, with a 2.2% drop in shooting victims, to 44 from 45.

Police made 1,827 arrests related to the convention last week, but most of those arrests were for disorderly conduct violations and were not reflected in Compstat.

The greatest problems arose on August 31, when 1,000 people were arrested in a 4-hour period, overwhelming the post-arrest screening site at Pier 57. Police Commissioner Raymond Kelly said half the arrestees were women and 65% were from out of state, which further bogged down the process.

Mr. Kelly said temporary unavailability of fingerprint verification identification systems and other computer programs contributed to delays. He called allegations that the city intended to hold arrested protesters until the convention concluded on Thursday “patently false.”