Delhi Chief Minister and Aam Aadmi Party (AAP) National Convenor Arvind Kejriwal on Thursday questioned the credibility of the "open challenge" by the Election Commission (EC) to hack its electronic voting machines (EVMs).

Kejriwal wondered as to why the poll panel had not issued a formal statement about the challenge and reports came in the media attributing it to sources.

"Has anyone actually seen any official statement from CEC (Chief Election Commissioner)? Am trying to get it since eve. Is this news correct," Kejriwal said in a series of tweets.

"Why are these stories ascribed to 'sources'? How credible are they? Why hasn't EC issued any formal statement? Or is it just a plant?" he added.

Deputy Chief Minister Manish Sisodia also tweeted on the issue asking as to why the EC's "open challenge" was not in the "open" and being run through the media.

"Why this 'open challenge' is coming out through a 'leak' to media? No letter or press release from EC so far," Sisodia tweeted.

EC sources had on Wednesday said that the poll panel was going to invite experts and stakeholders to try and hack EVMs in May, in order to clear all doubts about the voting machines' credibility.

Opposition parties have been questioning the integrity of EVMs since the results of assembly elections to five states were declared on March 11.