The government on Wednesday revised down the Gross Domestic Product growth rates for the 2006-2012 period, saying it had recalibrated the data to reflect a more accurate picture of the economy.

In August, the National Statistical Commission had released the back series data – older GDP data revised in line with the new series – which showed India’s economy had grown by over 10% for at least one year when the United Progressive Alliance, led by the Congress, was in power. India changed the base year for calculating GDP growth to 2011-’12 after the Narendra Modi government took over. In the absence of a back series, GDP data for the years before the new method was introduced was considered incomparable to that for the later years.

After the data released by the National Statistical Commission showed the economy had grown faster during the previous government, the Modi administration issued a clarification saying it was not an official estimate and was only meant to facilitate a decision on the appropriate approach for calculating a back series.

According to the new data released by the Central Statistics Office on Wednesday, the economy grew by 8.5% in 2010-’11, not by 10.3% as estimated by the commission.

“Back series released today by the CSO has been checked for its methodological soundness by leading statistical experts in the country,” NITI Aayog said in a statement. The government agency said the quality of coverage and methodology were ensured by experts who participated in two round tables it had organised.

“The new GDP series is superior than older one,” NITI Aayog Vice Chairman Rajiv Kumar said, according to Moneycontrol. “A complex exercise has been carried out by the Ministry of Statistics and Programme Implementation to update the National Accounts Series. The new series has made significant methodological improvements.”

‘Niti Aayog’s revised GDP numbers are a joke’: Chidambaram

Former Union Finance Minister and Congress leader P Chidambaram called the NITI Aayog’s revised GDP numbers a joke. “The numbers are the result of a hatchet job,” Chidambaram said on Twitter. “Now that Niti Aayog has done the hatchet job, it is time to wind up the utterly worthless body. The earlier numbers were calculated by the National Statistical Commission. Has the commission been disbanded?”

The Congress accused the Modi government of “manipulating” the GDP data of previous years, PTI reported. “The entire GDP back series data released today reflects the desperate attempt of a defeatist Modi government to undermine India’s growth story over last 15 years,” Congress spokesperson Randeep Singh Surjewala said in a statement. “Modi Government and its puppet Niti Aayog want the people to believe that 2+2=8. Such is the gimmickry, jugglery, trickery and chicanery being sold as back series data.”

Surjewala alleged that a failed “Modinomics plus a pakoda economic vision” has put India’s economy in turmoil. He also blamed demonetisation and the Goods Services Tax introduced by the Modi government of causing an “economic mayhem”. He alleged that the government was trying to “hide the enormous body blow” caused by them to India’s economy.

Surjewala said the government had caused confusion by changing the base year from 2004-’05 to 2011-’12. He said that the party had repeatedly pointed out that when the base year is changed, the government should also revise the numbers for previous years.