Felonies committed by non-Japanese last year numbered 228, an increase of 41, or 21.9 percent, over the previous year, the National Police Agency said Thursday.

Arrests in the 228 cases, including those of murder, robbery, rape and arson, came to 251, an increase of 38 people, or 17.8 percent, over the previous year, the NPA said.

In a report released Thursday, the agency said police last year conducted full-scale investigations into 5,759 major crimes, which, in addition to the felonies mentioned, included kidnapping and organized theft.

That figure represents a rise of 795, or 16 percent, over 1997. As a result, police arrested 965 non-Japanese, a rise of 115, or 13.5 percent, according to the report.

The agency noted in the report that the nation is increasingly vulnerable to illegal aliens, whose methods of smuggling themselves into Japan have become more sophisticated.

Police also noted that some Iranians are still actively involved in illegal drugs and narcotics sales in Tokyo and other Japanese cities. They arrested 289 Iranians in drug cases last year, compared with 328 for the previous year. This was still about eight times the figure of 38 people for 1992.

By felonies, 130 robberies occurred, about 1.5 times the number for the previous year, and 160 people were arrested; 43 rapes occurred, compared with 17 for 1997, according to the report.