"Whatever they have done is illegal and unconstitutional," Sandhu told reporters here.
He claimed the decision was a violation of the AAP's constitution and that the party did not give them a chance to explain.
"It is in the party's constitution that before taking any disciplinary action against a member, MLA or MP, one should be given an opportunity to explain his position. But we were not given any notice and the party sought no explanation from us," Sandhu said.
He claimed that the party constitution mandates the formation of a disciplinary committee before taking action against any member and a Lokayukta takes the final call.
None of this was done in this case, the Kharar MLA said.
"There is no mention of the core committee in the party's constitution," he claimed.
Meanwhile, the AAP's rebel faction, in a meeting of its ad hoc Political Affairs Committee (PAC), decided to form a three-member disciplinary committee comprising Sandhu, Pirmal Singh and Karanjit Kaur.
"This disciplinary committee will issue a show cause notice to the party's core committee, asking why it took this unconstitutional decision," Sandhu said.
"There have been many complaints of irregularities in use of funds against national leaders of the party. Our disciplinary committee will probe these complaints and then issue a white paper on it. The final decision will be taken by the Lokayukta," Khaira said.
The suspension of Khaira and Sandhu came nearly three months after the former was removed from the post of Leader of Opposition in Punjab Assembly and following AAP national convenor Arvind Kejriwal's visit to Chandigarh on November 3.
The rebel group has been seeking autonomy for the state unit, which they say was being controlled by the Delhi leadership.
Out of the total 20 MLAs, Khaira has eight legislators on his side.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)