Mulla alleged that he felt "betrayed" and "used" by the Congress for their "selfish gains".
He went on to add that Congress has no future left in the coastal state.
Former Goa Cricket Association (GCA) treasurer Mulla is amongst the three persons arrested for alleged forgery and misappropriation of GCA funds amounting to Rs 3.13 crore.
He was arrested by Economic Offences Cell of Goa police in June 2016.
"I felt betrayed and used by the Congress party for their selfish gains," Mulla said justifying his entry into GFP ending his 40-year long association with the Congress.
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"The Congress party has no more future in Goa. I appeal minority community not to stand by that party," said Mulla addressing a press conference in presence of GFP president Vijai Sardesai.
Responding to questions, Sardesai defended Mulla in GCA misappropriation case claiming that he was falsely implicated in the matter.
"The forensic report has clearly said that his signature was forged on the documents," said Sardesai.
The by-election for Valpoi and Panaji constituencies are scheduled on August 23.
In Valpoi, BJP has fielded Health Minister Vishwajit Rane while Congress has Roy Naik in the fray.
Meanwhile, Congress reacting to Mulla's statement said that he has been indulging in election gimmick.
"The way Goa Forward Party is poaching Congress leaders itself indicates that they are worried about their fate for the Panaji and Valpoi by-election," Congress leader Girish Chodankar said.
"Last minute attempts are made to confuse voters which will not work as they (voters) have already decided to elect Congress candidates," he said.