The development, which makes Gen. Singh the first serving chief of the armed forces to go to court on a service-related matter, comes 12 days after he told The Indian Express that “the thought (of approaching the court) has not occurred to me yet”.

The defence ministry and the government did not respond to the development on Monday. An official statement is expected tomorrow.

In his petition, Gen. Singh has delinked his disagreement with the government on his date of birth from the issue of his retirement. He is learnt to have clarified that his contention is not about his tenure, which is the prerogative of the government. He has asked the apex court only for directions on whether 1951 or 1950 should be taken as his correct year of birth.

The later year would make him eligible for another year in office.

The petition filed in the apex court by Gen. Singh’s lawyer U U Lalit could come up for hearing shortly. Sources said the plea seeks directions from the court on the date of birth, given that the defence ministry has fixed it as May, 10, 1950, while all other documents, including his matriculation certificate, record it as a year later.

As earlier reported, the Army Chief’s legal options were constrained by a public interest petition filed by an ex-servicemen’s association on the same issue.

The PIL, which names Singh as a respondent, is scheduled to come up for hearing on January 20. Had the court rejected the PIL, it would have affected the officer’s legal options.

The move to take the matter to the Supreme Court comes after Defence Minister A K Antony last month turned down a formal representation by Gen. Singh on the issue. The minister, however, wrote a separate letter to Gen. Singh, expressing confidence on his ability to lead the Army.