BEIJING -- Xi Jinping on Sunday stressed winning the tough and protracted battle against corruption.

"Corruption is a cancer to the vitality and ability of the Party, and fighting corruption is the most thorough kind of self-reform there is," said Xi at the opening session of the 20th National Congress of the Communist Party of China.

"As long as the breeding grounds and conditions for corruption still exist, we must keep sounding the bugle and never rest, not even for a minute, in our fight against corruption," Xi said.

The Party will continue to ensure that officials do not have the audacity, opportunity, or desire to become corrupt, he said.

Xi vowed zero tolerance in opposing corruption and punishing wrongdoing. "There must be no mercy for corruption."