Story highlights India's former finance minister has attacked Modi's handling of the economy

Criticism has provoked a rare public spat among senior party members

New Delhi (CNN) India's Prime Minister Narendra Modi, who came to power in 2014 with promises to boost the country's economy, is facing mounting criticism from within his own party amid concerns about slowing growth.

Modi's Hindu nationalist Bharatiya Janata Party (BJP) won a landslide victory in the last Indian general election, following a high-octane campaign that portrayed the 67-year-old as an economic reformer who would drive growth and create jobs for India's youthful population.

But the latest reading of India's GDP showed that growth had declined to 5.7% in the three months to the end of June — the lowest in three years.

Now, as the economy hits the buffers, a veteran leader from Modi's party who oversaw the Indian economy in the early 2000s has launched a stinging rebuke of Modi's handling of the current situation, giving rise to an unusually public spat within the ruling party.

In an op-ed piece for the local Indian Express newspaper , Yashwant Sinha, who has twice served as India's finance minister, made reference to Modi's humble roots as the son of a tea-seller while blaming his government for the weakness in growth.

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