"It is a serious allegation leveled by Kejriwal's former minister...He should step down immediately on moral grounds," Gandhi, an MP from Patiala, told PTI.
Gandhi was suspended from AAP for alleged anti-party activities in 2015, following which joined Apna Punjab Party (APP).
Demanding a CBI probe into the matter, he said that the allegations leveled by Kejriwal's former minister must be probed by the CBI, under the monitoring of the Supreme Court.
Gandhi, who floated 'Punjab Front' ahead of recently concluded Assembly polls in Punjab, said "a progenitor has killed his progency once again."
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His outfit fielded candidates on ten seats in Punjab polls, but it failed to make any impact.
He said with today's allegations of corruption by a former minister against Kejriwal the dream of India of honest alternative politics stood aborted.
He claimed that the AAP had started to disintegrate after the results of Assembly polls in Punjab, Goa, Delhi municipal corporation and bypoll to Rajouri Garden Lok Sabha seat were announced.
"He (Kejriwal) has done a lot of damage to the country," he said, adding that he had deceived people.
"Kejriwal should immediately resign on moral grounds and be open to probe," said Chhottepur, who was suspended from AAP in 2016 after allegations of corruption surfaced against him.
He alleged that few people, like Deputy CM Manish Sisodia, around Kejriwal keeps hiding his false promises.
"He (Kejriwal) use to throw people out of AAP on mere allegations, without having any evidence. He used to teach people the lesson of honesty," he said.
Earlier in the day, sacked Delhi minister Kapil Mishra accused Kejriwal of taking Rs 2 crore from his cabinet colleague, a charge refuted by Deputy CM Manish Sisodia.
The allegation by Mishra, who was sacked from the AAP dispensation last night, came amid growing rumblings in the Aam Aadmi Party (AAP).