Major crimes spiked by more than 12 percent after the number of stop-and-frisks conducted by the NYPD dropped dramatically earlier this year, The Post has learned.

Figures show there were 24,751 major crimes committed between Jan. 1 and March 31, a period when cops stopped 203,500 individuals and recovered 881 guns, according to sources.

In the following three months — between April 1 and June 30 — the number of stop-and-frisks cops conducted fell to 133,934 and the crime figures shot up to 27,832. The number of guns seized fell to 732.

There was no further analysis of the crime data immediately available.

But on the face of it, the statistics seem to provide the NYPD with evidence that — at least in this one period — more stop-and-frisks resulted in fewer crimes and more gun seizures.

The relationship between the latest stop-and-frisk numbers and crime statistics could provide critical ammunition in the battle over the policing tactic, which has come under fire from activists like the New York Civil Liberties Union and a chorus of elected officials.

Mayor Bloomberg has steadfastly defended the program as a life-saver and slammed the NYCLU for pushing to dismantle it.

“If the NYCLU is allowed to determine policing strategies in our city, many more children will grow up fatherless and many more children will not grow up at all,” he said last month at a Queens church.

“Let’s be clear. The NYCLU’s priority is not protecting our safety, it is protecting their ideology. And in that regard, they are no better than the NRA.”

Unrelenting critics of the controversial practice kept piling it on yesterday, even after Police Commissioner Ray Kelly confirmed that 34 percent fewer people were stopped in the latest period measured.

“It is encouraging to see the numbers begin to come back to Earth,” declared Public Advocate Bill de Blasio.

“But we need to look beyond this one statistic to know if City Hall has truly heeded the voice of communities across the five boroughs. Reform does not end here.”

The message was virtually the same from the NYCLU, which called the latest stop-and-frisk numbers “encouraging” before unleashing another attack.

“If past is prologue, we can expect that NYPD officers subjected at least 1,000 innocent New Yorkers a day to humiliating and unjustified street stops,” said NYCLU executive director Donna Lieberman.

“That is nothing to brag about. This reduction is a good start, but much more needs to be done to rebuild community trust.”

Critics had been demanding that the NYPD bring down the numbers, which is just what it did in rather dramatic fashion.

If the lower pace achieved from April to June continues through the remainder of the year, it will be only the second time during the Bloomberg administration that year-to-year figures would show a decline. The last time that happened was in 2007, when there were 472,096 stop-and-frisks, compared to 506,491 in 2006.

About half of those stopped get patted down.

Kelly attributed the latest reduction to two developments first spotlighted by The Post: restoring about half the 2,000 rookie cops to precincts who had flooded high-crime neighborhoods early in the year and new training.

“We are now training more specialized units in a more focused way of conducting stop and questions and sometimes frisk practices,” he said. “We are hopeful that the training is improving the quality of stops.”