Amid speculation that the citywide murder rate is on course to set a record low, the New York City Police Department is planning to step up its operations in high-crime areas across the city, the police commissioner, Raymond Kelly, announced yesterday.

Every cadet who graduates from the police academy today at Madison Square Garden will be deployed to the department’s Operation Impact, an initiative that floods high-crime areas with rookie police officers on foot patrol, Mr. Kelly said.

With about 900 cadets set to graduate, the Impact program will double in size and have more officers assigned to it than ever before, he said.

Roughly one-third of all Impact officers will be deployed to Brooklyn, with a significant number of new officers assigned to Bedford-Stuyvesant and Crown Heights, the commissioner said.

Increasing the size of the operation marks a dramatic turnaround for the program, which until yesterday appeared to be on its last legs.

Because of the department’s recruiting problems, Mr. Kelly had said several times in the past few months that the future of Operation Impact was in jeopardy.

However, an analysis performed by the department led top officials to believe that the program, which Mr. Kelly yesterday said is the prime reason crime has decreased in the city under his watch, could be augmented.

The decision was in large part due to the likelihood of declining attrition rates within the department, he said.

In 2008, the number of officers reaching their 20th anniversary, a milestone at which about 81% of city police officers retire, will decrease by about 4,200 compared to 2007, Mr. Kelly said.

The move also marks a change in department policy toward recruits. Previously, two-thirds of each graduating class and an appropriate number of supervisors were assigned to the Impact program.

After six months, those officers were replaced by the next graduating class and transferred to regular precinct duty.

Under the new plan, current Operation Impact officers will not be reassigned until further evaluation of the program, Mr. Kelly said.

The commissioner announced the changes to the program at a press conference yesterday with Mayor Bloomberg, where the two touted crime reductions this year throughout the city.

The murder rate for 2007, which, according to police statistics, was at 484 yesterday, will likely be fewer than 500, Messrs. Bloomberg and Kelly said.

That would be the fewest murders in the city since 1963, the last year in which crime statistics can reasonably be compared, a spokesman for the department, Deputy Commissioner Paul Browne, said.