A spokeswoman with China's top legislature Tuesday vowed "zero tolerance" of election fraud and severe punishment on offenders.

The election fraud in central China's Hunan Province has been the worst in the history of the National People's Congress (NPC), said Fu Ying, spokeswoman for the NPC annual session, at a press conference.

The fraud case was "severe in nature" and exerted "a very bad impact," she said.

In an election of provincial legislators in Hengyang City of Hunan in late 2012 and early 2013, 56 city lawmakers offered bribes to 518 of their fellow lawmakers and another 68 staff in order to get elected.

The total amount of money involved exceeded 110 million yuan (18.14 million U.S. dollars).

The involved lawmakers have been disqualified, dismissed or resigned in December last year.

The NPC will firmly safeguard the authority of the Constitution and laws and the system of people's congress, Fu said.

"Any act undermining the legislative election, no matter who are involved and where it takes place, should be severely punished," She said. "There is no exception."

NPC deputies should set an example of abiding by laws and respect the will of the people, she added.