NEW DELHI - An Indian court on Thursday sentenced Rahul Gandhi, leader of the largest opposition party, the Indian National Congress, and a scion of past prime ministers, to two years' imprisonment after he was found guilty of defaming Prime Minister Narendra Modi in a speech at a 2019 campaign rally.

A court in Modi's home state of Gujarat announced the conviction, then immediately suspended the jail sentence for 30 days, during which Gandhi can appeal. The defamation case was initially brought in 2019 by Purnesh Modi, a local politician in Modi's Bharatiya Janata Party (BJP), after Gandhi asked a crowd in southern India why two prominent fugitive business executives and the sitting prime minister all shared the Modi surname - and happened to all be "thieves."

The court decision came at a time when Gandhi, a member of Parliament and the face of the Congress party, is facing escalating political and legal peril as he dials up his criticism of the Modi government. If his appeal fails, he could be barred from contesting elections or holding office for six years.

In the past week, police forces under the central government's command arrived at Gandhi's home in New Delhi to question him over public remarks he made about the prevalence of sexual assault cases in India. The BJP has also demanded that Gandhi be suspended from Parliament as punishment for a speech he made in Britain in which he accused Modi of dismantling Indian democracy.

Responding to the court decision Thursday, Congress vowed to appeal the judgment and said the government was using the police, investigative agencies and courts to persecute its political rivals.

"Rahul Gandhi is raising his voice against a dictator and showing the courage to call what's wrong, wrong," the party said in a tweet. "This dictator is rattled by courage."

The Aam Aadmi Party (AAP), which controls Delhi and Punjab state and competes vigorously with the Congress party to become India's main opposition party, called the court decision a "conspiracy" to squash dissent.

"Opposition forms [the] core of democracy. Dissent should not be stifled," AAP spokesman Raghav Chadha tweeted. "Attempt to reduce this to [the] viewpoint of one ideology, one party, one leader is unconstitutional & undemocratic."

BJP officials, meanwhile, doubled down, saying Gandhi had defamed not only Modi but lower-caste citizens more broadly. In India, surnames often denote a person's caste or community, and Modi belongs to the Modh-Ghanchi community, who are traditionally small-business owners.

The BJP often contrasts Modi's modest upbringing with Gandhi's privileged background - he is the grandson of former prime minister Indira Gandhi and great-grandson of India's first leader Jawaharlal Nehru - as part of its political messaging.

Ravi Shankar Prasad, a senior BJP lawmaker, said Thursday that Gandhi was being appropriately punished for voicing "caste-related abuses."

"The law of India has it that if an individual or an organization has been defamed with scurrilous statements, scandalous comments, abuses or any defamatory remarks, then he or she has a right to seek redress," Prasad told reporters.

In recent weeks, critics of the Modi government have increasingly found themselves under scrutiny by tax and law enforcement authorities.

In February, Indian tax officials raided the BBC's offices in New Delhi and Mumbai after the broadcaster aired a critical documentary about Modi on British airwaves - but not in India. Days after that, a Congress party spokesman was arrested by police under orders from BJP officials for making a sarcastic remark suggesting that Modi was so beholden to the Indian tycoon Gautam Adani that he was the billionaire's son.

Gandhi himself became the focus of the BJP's ire after he departed late last month for a 10-day visit to Britain.

In a series of appearances at Cambridge University, the Chatham House think tank and the British Parliament, Gandhi told audiences that the Indian government was undermining the free press, abetting attacks on minorities and surveilling opposition figures using sophisticated spyware. Yet the United States and Europe, the "so-called defenders of democracy," were apparently "oblivious" to how one of the world's most important democracies was unraveling, Gandhi said as he chided Western leaders for their reluctance to criticize the Indian government.

Back home, BJP officials construed Gandhi's remarks as an appeal for Western intervention in Indian politics and warned he would pay a price. Days after he returned, police repeatedly visited Gandhi's home to inquire about his comments about sexual violence in India, which Congress said amounted to harassment by the state. Last week, BJP lawmakers asked the parliamentary speaker to suspend Gandhi from the legislative body.

"We won't allow anti-India forces to destroy India's image and our rich democratic legacies," said Modi's law minister, Kiren Rijiju. "India will never forgive [Gandhi] and his entire gang members who deliberately worked to tarnish the virtuous image of India."