Singh, who was a Congress member in the House, was expelled in December 2005 from Parliament for allegedly accepting bribes for asking questions.
His son Dharamveer Singh claimed that 31 questions pertaining to different ministries were submitted in his father's name in August 2005.
The Lok Sabha Secretariat informed his father about the signatures not matching after verification, he said.
He claimed that his father signed in English, but the questions submitted to the Lok Sabha had his father's signature in Hindi.
More From This Section
However, after his father was expelled from Parliament for allegedly accepting bribes for asking questions, Dharamveer decided to pursue the matter.
"My father was ill for more than two years after 2005. It was in 2008 that I started filing RTIs to get details about the matter," he said.
The Lok Sabha Secretariat, in a reply to the Central Information Commission, last year accepted that the signature on the questions allegedly submitted by the former MP were forged and asked the MP to approach the police, he said.
According to the FIR, "The question wing of Lok Sabha Secretariat addressed a letter dated August 12, 2005 to the undersigned that the request letter seeking questions proposed to be raised in Parliament under his name do not contain the authentic signatures, thus varying from the records as available with Parliament."
In his complaint, the former MP has claimed that even though he pursued the issue, no action was taken.
A senior police officer said that a case under sections relating to forgery for purpose of cheating and using as genuine a forged document or electronic record of the Indian Penal Code has been registered and an investigation is underway.