Modi made the claim about the disputed strip of water body in a letter to Prime Minister Manmohan Singh on the eve of the Gujarat Assembly polls but the PMO lost no time to debunk it.
The first phase of the two-phase Assembly elections in Gujarat is being held tomorrow. The second phase is on December 20.
"Allegation in the letter that Sir Creek is about to be given to Pakistan is untrue... The other conclusions drawn by Shri Modi on this alleged fact are also not real," the PMO said responding to Modi's letter.
Raising questions over timing of the letter, PMO said, "The contents of the letter and the timing of its release to the public raise questions about the motives behind its issue...The writing and release of this baseless letter by the CM of Gujarat in his "personal" capacity, a day before elections, is mischievous."
It said the Gujarat Chief Minister has written the letter without making any efforts to ascertain the facts from the Government of India.
Finance Minister P Chidambaram termed as "ridiculous" Modi's claim about Sir Creek and asserted nobody was going to give it to the neighbouring country.
In the letter to the Prime Minister, Modi also said India should stop dialogue with Pakistan on the Sir Creek issue.
"I am writing on a serious issue of talks being held on Sir Creek being handed over to Pakistan. Any attempt to hand over Sir Creek to Pakistan would be a strategic blunder considering the history and sensitivity of the region," the BJP leader said.
"I would earnestly request you to stop this dialogue with Pakistan at once and Sir Creek should not be handed over to Pakistan," Modi further wrote in the letter.
"Due to the election code of conduct, Modi wrote the letter as a concerned citizen and not as a chief minister of a state," BJP spokesperson Nirmala Sitaraman said while giving details of the letter at a press conference in Ahmedabad.
"I am writing to you at this juncture as I was told that a decision is being taken on Sir Creek issue on December 15," Modi said in the letter.
Modi voiced his apprehension ahead of Pakistan Interior Minister Rehman Malik's planned visit to Delhi from December 14 to discuss a range of bilateral issues.
