The PMO cited the resignation letter written by Gandhi to outgoing Prime Minister and the then Chairman of the Committee, Manmohan Singh, on May 21, five days after BJP won the Lok Sabha elections.
"I am writing to say that as an appointee of the outgoing UPA government, I wish to resign from the membership of the National Committee for the commemoration of 125th Birth Anniversary of Shri Jawaharlal Nehru. I would be grateful if my resignation is accepted with immediate effect," the letter said, according to PMO sources.
The sources said Singh had accepted the resignation.
"She (Sonia Gandhi) had already opted out of the committee long back," a PMO source said while seeking to justify the exclusion.
The justification came after it was highlighted by the media that no member of the Gandhi family found a place in the committee reconstituted by Prime Minister Narendra Modi on Saturday.
The committee, headed by Modi, however, includes some Congress leaders -- Ghulam Nabi Azad, Mallikarjun Kharge and Karan Singh.
Nehru's 125th birth anniversary falls on November 14 this year.