NEW DELHI (REUTERS) - India's government has asked Mr Rahul Gandhi, the president of the main opposition Congress party, to respond to a complaint by a lawmaker from Prime Minister Narendra Modi's party accusing him of holding dual British citizenship against Indian law.
Mr Gandhi, the scion of the Nehru-Gandhi dynasty that has dominated Indian politics for much of its history since independence from Britain in 1947, is the main challenger to Mr Modi in the 39-day general election that began on April 11.
Results will be known on May 23.
Congress dismissed a notice sent to the 48-year-old Mr Gandhi, who has studied and worked in England, by the Ministry of Home Affairs on Monday as a "pathetic stunt that is not just frivolous but downright stupid".
The notice was based on a letter from Mr Subramanian Swamy, an outspoken MP from Mr Modi's nationalist Bharatiya Janata Party (BJP).
Mr Swamy has for long cited what he calls annual reports and other documents from 2005, 2006 and 2009 of a UK-registered company, at which Mr Gandhi was a director, as mentioning his nationality as British.
"You are requested to intimate the factual position in the matter to this ministry within a fortnight of the receipt of this communication," Mr B.C. Joshi, a director in the Indian Interior Ministry, said in the notice to Mr Gandhi.
Federal Home Minister Rajnath Singh, also a senior BJP leader, told reporters his ministry was following due process.
India's Constitution says that any person voluntarily acquiring a foreign passport automatically loses Indian citizenship.
Congress said the BJP was making fake, personal attacks on Mr Gandhi after sensing defeat in the election. Mr Gandhi has been a member of India's Lower House of Parliament since 2004 and is contesting this election from two seats.
"This is outrageous, outlandish and obtuse," Congress spokesman Sanjay Jha said. "The people of India can see through these malicious and malevolent personal attacks."
The BJP earlier protested against any constitutional post for Mr Gandhi's Italian-born mother, Mrs Sonia Gandhi, who famously gave up on the chance to become India's prime minister despite Congress winning the 2004 election under her presidency.
She became an Indian citizen in 1983.