Special CBI judge OP Saini told a packed courtroom: "I have absolutely no hesitation in holding that prosecution has miserably failed to prove any charge against any of the accused, made in its well-choreographed charge-sheet."

Judge Saini scathingly ruled in a 2,000-page order that "...some people created a scam by artfully arranging a few selected facts and exaggerating things beyond recognition to astronomical levels."

A Raja, who defended himself in court and even cross-examined witnesses, said he was "delighted". The former minister has been on the sidelines after spending nearly a year in prison in 2011-12.

M Kanimozhi, the daughter of DMK chief M Karunanidhi, beamed as she told NDTV: "Justice has prevailed." For the DMK - which was a Congress ally in the first UPA government before the scandal exploded - the order means political resurrection after years of struggling with the 2G taint.

The CBI had alleged that a telecom company paid Rs 200 crore in bribe to Mr Raja, which was deposited in a TV channel in Chennai part-owned by Kanimozhi.

The Congress, which lost power in 2014 in a haze of corruption allegations including the spectrum scandal, demanded an apology from the BJP. "Our zero loss theory on 2G spectrum allocation has been vindicated," said former minister Kapil Sibal.

In response, Finance Minister Arun Jaitley referred to the 2012 Supreme Court ruling: "That this was a corrupt, dishonest policy was upheld by the Supreme Court in February 2012. Each and every case of spectrum allocation was quashed by the Supreme Court as unfair and arbitrary."

The "2G" trial began in 2011, a year after the national auditor alleged that there had been massive irregularities in the allocation of second generation or 2G licences when Mr Raja was minister. The auditor, Vinod Rai, said licences were given to telecom operators in 2007-2008 at throwaway prices without a bidding process.

Named along with Mr Raja were the promoters and top executives of some of India's best-known telecoms including the one owned by Anil Ambani's conglomerate.