A unit of Pelican Bay prison in California. (Michael Montgomery/KQED).

Nearly 250 more criminals will serve their time in county jails instead of state prisons each year under a new California law, a sharp increase from the state's original projections.

The corrections department said Thursday that it miscalculated the effect of changing where some criminals serve their time.

Republican lawmakers say the shift that took effect last month will send more violent offenders to local facilities, violating the state's pledge to keep people convicted of violent crimes in state prisons.

Corrections officials originally said only two more criminals each year were likely to shift to local jails while serving time for weapons possession and other crimes. Those projections were reported in an Associated Press story published June 30.

The department now says 247 more criminals would go to local jails.

The population of the state's 33 adult prisons has dropped by more than 40,000 inmates since October, when the state began sending thousands of criminals to county jails in response to court orders requiring a reduction in overcrowding at state prisons.

The law enacted last month as part of the new state budget shifted 10 crimes back to state prisons, including several involving child sex offenses or seriously injuring a peace officer. The department projected that would affect about 10 criminals each year. Callison could not immediately say if researchers also miscalculated that estimate.

The AP first reported in October that at least two dozen offenses moving to local control could be considered serious or violent.

The additional crimes that will now bring jail sentences instead of prison time under the new law include possession of certain explosives, various knives and exotic weapons, as well as check fraud and defrauding the state's food stamp program.

Officials said they were merely fixing a drafting error, and that those categories of crimes should have resulted in jail time under the original realignment law that took effect last year.