LONDON, March 6 (Reuters) - Exiled Belarusian opposition leader Sviatlana Tsikhanouskaya was handed a 15-year jail term on Monday after being convicted in absentia for treason and "conspiracy to seize power", a verdict she said was punishment for her efforts to promote democracy. Tsikhanouskaya's own husband, Syarhei, is serving an 18-year jail term after being found guilty in 2021 of organising mass unrest in a ruling she said was political revenge and part of a crackdown by Lukashenko on anyone he viewed as a threat. See here for a complete list of exchanges and delays