TOKYO, Jan 13 (Reuters) - Tokyo recorded a new four-month high in COVID-19 infections on Thursday, and experts forecast the spread of the Omicron variant will cause the daily count to triple by month"s end. Japan"s capital had 3,124 new coronavirus cases, the most since Sept. 1. The daily tally will likely exceed 10,000 by the end of January, according to projections announced at a municipal government meeting. Nationwide cases exceeded 18,000 on Thursday, about 5,000 more than the day before, broadcaster TBS reported. The western prefecture of Osaka reported 2,452 new cases, the highest since Sept. 2. Omicron now accounts for more than 80% of new infections in Japan, Chief Cabinet Secretary Hirokazu Matsuno told reporters. Japan on Sunday stepped up coronavirus restrictions in three regions that host U.S. military facilities, after it appeared that Omicron outbreaks at the bases spilled into the surrounding communities. read more Tokyo Governor Yuriko Koike said on Thursday the capital would request similar measures if usage of critical care hospital beds climbed to 20%, from about 14% presently. A full declaration of emergency would be called for if the rate rises to 50%, she added.