NEW YORK, Dec 30 - U.S. chain store sales jumped in the run-up to Christmas as a last-minute surge in bargain hunting set retailers up for the best seasonal performance since 1999, a report said on Tuesday. Sales climbed 2.0 percent in the week ended Dec. 27, up from a 0.6 percent gain the week before, the International Council of Shopping Centers and UBS said in its joint report. Compared with the previous year, sales for the week rose 5.5 percent, only slightly down from the previous week's 5.7 percent. Sales in the latest week exceeded their prior five-year median comparison and ICSC now expects sales for all of December to grow between 4.0 percent and 4.5 percent. The ICSC noted some mall managers reported strong gift certificate redemption which clearly added to sales growth in the period. The ICSC-UBS Weekly Chain Store Sales Snapshot is compiled from a group of major discount, department and chain stores across the country that report their weekly results. The index measures sales growth with the year 1977 equaling 100.//