According to a press release, the National Bank of the Republic of Belarus introduced new 100-ruble (US$0.02) and 5,000-ruble (US$1) banknotes dated 2000. Both denominations retain their current designs (B126a and B128a, respectively). The solid security thread is eliminated from the 100-ruble note as a cost-saving measure, whereas the 5,000-ruble note saw its security thread changed to a windowed thread with demetalized НБРБ, to strengthen its counterfeiting deterrence. The existing notes of the same denominations remain legal tender.
Courtesy of Vitali Khaletski, Didier Wiot, and Ivan Bogdanov (http://bonistics.org).