NEW DELHI, Jan. 1 (Xinhua) -- A military court has ordered the sacking of a high-ranking Indian Army officer after sentencing him to three years in prison for an extra-marital affair with a sub-ordinate officer's wife.

The general court martial under the Eastern Army Command based in the eastern city of Kolkata handed down the punishment to an Indian Army brigadier last week, revising its earlier order of a lighter punishment of a loss of 10 years of seniority after he pleaded guilty.

The initial punishment by the court in October last year was revised only after an intervention by the Indian Army headquarters in Delhi, defense sources said Monday.

The extra-marital affair of the brigadier (who name has been withheld) came to light last year after his wife, who works as a teacher in a reputed school in the Indian capital, complained to the Indian Army, prompting an immediate inquiry.

The officer's wife submitted proofs like sexual messages exchanged between her husband and his "lover" on social media like WhatsApp to corroborate her allegations.

A subsequent probe by the Indian Army revealed the affair between the officer, who was then posted in Siliguri town under the Eastern Command, and the wife of a sub-ordinate officer. Both had initially rejected the affair, but the officer later pleaded guilty in the court.

In the Indian armed forces, an affair with a "brother" (another officer) is considered to be a major offense that entails a court martial.

But such incidents are not uncommon in the Indian armed forces.

The Indian Air Force last year sacked a fighter pilot for an affair with a senior officer's wife at an airbase in the western state of Rajasthan. Similarly, the Indian Navy sacked two commanders in Mumbai for extra-marital affair and sending lewd messages to women.