A notorious former police chief whose revelations have shaken Spain's elite to the core, said Wednesday he had been treated like public enemy number one as he went on trial for blackmail and corruption.

"They haven't treated me like a suspected criminal, they've treated me like an enemy that needs to be destroyed," complained Jose Manuel Villarejo in remarks to the press before taking the stand on the first day of a massive espionage trial involving 27 people.

"In this country, when someone is a nuisance, they annihilate and destroy them, unfortunately making use of institutions as serious as the justice system," said Villarejo, turned up to Spain's top criminal court wearing a dark beret and sunglasses.

The 70-year-old is accused of having secretly recorded conversations with the rich and powerful to either blackmail or discredit them on behalf of other prestigious clients.

Over the last few years, dozens of powerful businessmen, high-ranking civil servants, ministers and magistrates have been tainted by scandals involving this feared former policeman at the heart of the so-called "sewers of state".

Although Villarejo is implicated in multiple cases, Wednesday's trial was focused on just three, all involving businessmen suspected of using his services to spy on both colleagues and competitors.

L'ex-commissaire espagnol José Manuel Villarejo au premier jour de son procès à San Fernando de Henares, près de Madrid de Madrid, le 13 octobre 2021
L'ex-commissaire espagnol José Manuel Villarejo au premier jour de son procès à San Fernando de Henares, près de Madrid de Madrid, le 13 octobre 2021 POOL / FERNANDO VILLAR

He has already served three years of pre-trial detention but if convicted, he could face 109 years in jail, if prosecutors get their way.

On leaving the Audiencia Nacional in San Fernando de Henares, near Madrid, he said he had "absolute confidence" in the court.

"I trust that this is a country governed by the rule of law and that there won't be any kind of mob justice, which would end up being like a lynching," he said.

Several heavyweights of Spanish finance and industry, including former head of BBVA bank Francisco Gonzalez and Ignacio Galan, chief executive of Spain's top energy firm Iberdrola, have been accused of using his services.

In recent years, several top politicians have had their names dragged through the muck over their alleged connection with Villarejo, such as former interior minister Jorge Fern?ndez D?az, who is suspected of trying to smear political opponents.

Villarejo's involvement with the high and mighty even reached to the royal palace, damaging Spain's former king Juan Carlos I after the policeman secretly recorded a conversation with his mistress in which she claimed he had pocketed money from a high-speed train contract with Saudi Arabia.

"I understood it was my obligation to do what I did.. in other words to denounce all the illegality that I was seeing," Villarejo told reporters.