The IAF chief said that by acquiring the French fighters, the IAF would also be able strengthen its depleting fleet of fighters at a time when India's neighbours were "not sitting idle" and continuously modernizing their air warfare capabilities.

Speaking at a seminar here, Air Chief Marshal Dhanoa said the Russian-made S-400 Triumf advanced air defence systems to be bought from Moscow would also enhance the capability of the air force.

"By providing the Rafale and the S-400 (anti-missile system), the government is strengthening the IAF to counter the shortfall of our depleting numbers of aircraft," he said.

"The hi-tech fighters like Rafale are needed because medium-tech fighters like Tejas alone cannot do."

He said the IAF was already down with only 31 squadrons from the sanctioned strength of 42. "Even when we do have 42 (squadrons), we will be below the combined strength of our two adversaries," he said, adding that the gap was being "partially fulfilled by getting the hi-tech aircraft.

"The question that is asked very often in public domain is why 42 squadrons when older aircraft like MiG-21s are being replaced by more capable aircraft.

"There are reasons (for that) because our neighbours are not sitting idle. Pakistan has upgraded F-16s and made them 4.5 generation as far as avionic electronics goes and is inducting JF-17 (from China) in large numbers.

"China is rapidly replacing its 2nd and 3rd generation fighters with 4th generation fighters and is developing 5th generation fighter which is likely to be deployed very soon."

He said very few countries were facing challenges like India, which is surrounded by "two nuclear-armed neighbours".

"We have to match neighbours Pakistan and China to tackle a two-front war. Intentions of our adversaries can change overnight. We need to match force level of our adversaries," he said.

The IAF chief's comments come a day after former Bharatiya Janata Party ministers Yashwant Sinha and Arun Shourie alleged Prime Minister Narendra Modi's "personal culpability" in the Rafale deal which they dubbed as the country's "biggest defence scam".

The procurement of 36 Rafale fighters from France's Dassault Aviation has come under fire from the Congress, alleging that the Modi government had compromised national security and bought the bombers at a higher price than what the UPA had negotiated with the French government.

Earlier this month, IAF Vice Chief Air Marshal S.B. Deo too endorsed the Rafale, saying the aircraft will give India "unprecedented combat capabilities".