Top Indian opposition figure Rahul Gandhi has vowed to keep fighting for democracy after blaming his expulsion from parliament on his demands for a probe into a key business ally of Prime Minister Narendra Modi.

"I will do whatever I have to do to defend the democratic nature of this country," he told reporters during a press conference on Saturday.

"They are used to everybody being scared of them," he said, in reference to the ruling party.

"I am not scared of them."

Gandhi, 52, was stripped of his parliamentary seat on Friday, a day after he was convicted of defamation in Modi's home state of Gujarat for a 2019 campaign-trail remark seen as an insult to the premier.

The removal from parliament of Modi's chief opponent comes at a time when the prime minister's relationship with Gautam Adani, one of India's most powerful industrialists, has been under scrutiny.

Modi has been a close associate of Adani for decades but the latter's business empire has been subject of renewed attention this year after a US investment firm accused it of "brazen" corporate fraud.

Gandhi's opposition Congress party has for weeks demanded a proper investigation by parliament of the allegations.

"I have been disqualified because the prime minister... is scared of the next speech that is going to come on Adani," Gandhi told reporters.

"I will continue to ask the question — what is the prime minister's relationship with Mr. Adani?"

Congress supporters held small protests in several cities around the country on Saturday to protest against Gandhi's removal as a lawmaker.

READ MORE: Top Indian opposition leader Rahul Gandhi disqualified from parliament

Due judicial process

Gandhi is the leading face of Congress, once the dominant force of Indian politics but now a shadow of its former self.

He is the scion of India's most famous political dynasty and the son, grandson and great-grandson of former prime ministers, beginning with independence leader Jawaharlal Nehru.

But he has struggled to challenge the electoral juggernaut of Modi's Bharatiya Janata Party (BJP) and its nationalist appeals to the country's Hindu majority.

He was expelled from parliament on Friday following his conviction on Thursday in the defamation case.

Gandhi was sentenced to two years imprisonment but walked free on bail after his lawyers vowed to appeal.

A BJP spokesman said Thursday that the court acted with "due judicial process" in arriving at its judgement.

Gandhi faces several other defamation cases in the country and a money-laundering case that has been snaking its way through India's glacial legal system for more than a decade.

Congress spokesman Abhishek Manu Singhvi told reporters on Friday that the verdict represented the "emasculation of democratic institutions by the ruling party".

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