India army chief says leak of his letter is 'treason'
In his letter earlier this month, Gen Singh said much of India's defence equipment was "obsolete" and the forces were "woefully short" of weapons.
It is the latest in a series of rows between the army and the government and the letter led to uproar in parliament.
On Wednesday, Defence Minister AK Antony told parliament that the "government is committed to doing all that is necessary to secure the nation".
In his letter, Gen Singh said India's air defence was "97% obsolete", the army lacked the equipment it needed and its entire tank fleet was "devoid of critical ammunition to defeat enemy tanks".
The infantry lacked "night fighting" capabilities and was crippled with "deficiencies of crew-served weapons", the letter added.
'An outrage' "This is an outrage. Official communication with the prime minister, the defence minister or anybody for that matter with the chief of the armed staff is privileged information," Gen Singh said in a statement.
"The leaking of the letter should be treated as high treason. This cynical approach to tar my reputation has to stop.
"The source of the leak has to be found and dealt with ruthlessly," the statement said.
The letter was leaked to the media and reported extensively on Wednesday.
The revelations dominated discussion in parliament on Wednesday with opposition MPs questioning the government over the issue.
Defence Minister Antony said the leak was "a breach of national security" and several MPs demanded that the source of the leak be identified and punished.
Some MPs blamed Gen Singh for the leak and demanded that he be sacked.
In a short statement in the Rajya Sabha, the upper house of parliament, Mr Antony said the government would take "appropriate action" on the letter.
India's armed forces have been attempting a modernisation drive in recent years that has made the country the world's top arms importer.
Analysts say the upgrade has been hampered by delays and a lack of planning.
Bribery allegation The general's letter follows allegations he made on Monday in an interview with The Hindu newspaper that retired Lt Gen Tejinder Singh had offered him $2.7m (£1.7m) to approve the purchase of 600 "sub-standard" vehicles of a "particular make".
Lt Gen Singh has vehemently denied the charges, saying the accusations are "totally false" and he has filed a court case against the army chief.
The defence minister admitted that the army chief had informed him about the bribe offer a year ago and ordered a probe by federal police.
Mr Antony said he did not act earlier on the general's bribery allegation as he had never received a written complaint.
Earlier this year, Gen Singh was involved in an acrimonious row with the government over his retirement age.
The general went to the Supreme Court to have his date of birth as recorded by the military - 10 May 1950 - changed to a year later so that it matched the date on his birth certificate and other documents.
But he dropped the case after the court indicated it could rule against him because he had already accepted three promotions that were based on the earlier date.
Changing the date would have meant that he could retire in 2013 instead of later this year.
Defence analyst Rahul Bedi told the BBC that the age row was a symptom of wider acrimony between the armed forces and the government that has threatened to undermine the defence modernisation drive.