The Indian government has ordered an inquiry into allegations that the government of the Indian state of Gujarat and its Chief Minister Narendra Modi spied on a woman in 2009.
The move came after two websites released recordings of alleged phone conversations between Mr Modi's aide Amit Shah and police officials.
Mr Modi is the prime ministerial candidate of the opposition Bharatiya Janata Party (BJP) in the 2014 polls.
The BJP has denied the charge.
BJP spokeswoman Nirmala Sitharaman accused the government of "political vindictiveness" and of conducting a "witch-hunt" against Mr Modi.
Mr Modi has been chief minister of Gujarat since 2001 and is credited with making it one of India's most prosperous states.
But he is also accused of doing little to stop anti-Muslim riots in 2002 that left more than 1,000 people dead.
He has always denied the allegations.
Now he is facing an inquiry into allegations his government illegally spied on a young woman.
"The cabinet has approved a proposal to set up a commission of inquiry... to look into the incidents of physical/electronic surveillance in the states of Gujarat and Himachal Pradesh and the National Capital Territory of Delhi, allegedly without authorisation," a government press release said on Thursday.
The panel is likely to be headed by a retired Supreme Court judge and will be asked to submit its report within three months, officials said.
The tapes appear to reveal that the woman was under illegal surveillance.
The websites alleged that "police followed her inside malls, restaurants, gyms and even when she visited relatives".
Although Mr Modi was not named in the conversations, there were several references to "saheb" [sir in Hindi], which the websites alleged were references to Mr Modi on whose orders they said the surveillance was carried out.
The BJP said the woman, a young architect, was "provided with protection on the request of her father because she was being harassed".
BJP spokeswoman Meenakshi Lekhi said that "we cannot disclose the nature of the case for obvious reasons". But she stressed there was "nothing illegal about it"
The case has been extensively covered in the Indian media, which dubbed it "snoop-gate" or "stalk-gate".