TAIPEI, March 30 (Reuters) - Taiwan and China must do everything possible to avoid war and it is the responsibility of both sides' leaders to ensure peace, former Taiwan President Ma Ying-jeou told a senior Chinese official on Thursday. Ma arrived in China on Monday, the first time a former or sitting Taiwanese president has visited the country since the defeated Republic of China government fled to Taiwan in 1949 after losing a civil war to Mao Zedong's communists. See here for a complete list of exchanges and delays