Terrorist acts against Americans have increased sharply this year, although the number of casualties has fallen, the State Department said.

The department also reported Monday that terrorism worldwide is rising.Incidents directed against Americans in the first nine months of this year rose to 157 from 108 in the corres-ponding period last year, it said. Three Americans were killed and 25 injured, compared with one death and 38 wounded in the earlier period.

Almost half of the attacks on Americans this year were bombings of U.S. oil company property in Colombia. No one was killed in these incidents.

The three American deaths were in Greece, Italy and Peru.

Terrorist incidents worldwide totaled 680 in the first nine months of this year, up from 655 in the same period last year. The number of casualties declined, however, to 278 killed and 875 wounded, from the year-earlier total of 443 killed and 2,014 injured.

Increases in terrorism in Asia, Latin America and Africa outweighed declines in Western Europe and other areas.