Typhoon Mirinae strengthened from a tropical storm over the Pacific Ocean east of the Philippines and may reach Luzon, where relief work continues after two recent cyclones, within three days.

Mirinae was 832 kilometers (520 miles) west-northwest of the American territory of Guam at 11 a.m. Philippines time, the U.S. National Weather Service said on its Web site. The center of the typhoon was about 1,720 kilometers east of the city of Baler on the east coast of Luzon.