Home Minister Rajnath Singh said Saturday no guilty person would be spared in the case relating to the leak of documents from the petroleum ministry and strong action would be taken against them.
Rajnath Singh said the government should be commended for unearthing the scandal.
"We should be commended as we found out that this was happening, the culprits will be punished," he told reporters.
"If we would have not been vigilant, this (scandal) should not have been busted," he added.
On Thursday, police arrested five people - two petroleum ministry employees and three others - for stealing documents and leaking them to corporate houses.
With seven arrests Friday, the total number of those held rose to 12.
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According to the police complaint, the stolen documents included inputs for the Union Budget 2015 and a letter concerning the Prime Minister's Office. The documents were also related to the power and coal ministries, police said.
The First Information Report details how the "secret papers" were photocopied after office hours by the arrested persons, who used duplicate keys to open offices after entering Shastri Bhawan with the help of forged identity cards and temporary passes obtained fraudulently.