The CIA read the encrypted messages of several countries, including India, for decades through its secretly-owned Switzerland-based company trusted by governments all over the world to keep the communications of their spies, soldiers and diplomats secret, according to a leading American daily.

According to a report by The Washington Post and German public broadcaster ZDF published on Tuesday, the company, Crypto AG, entered into a deal with America's Central Intelligence Agency (CIA) in 1951 and came under its ownership in the 1970s.

The joint reporting project, which uncovered the secret operation from CIA classified documents, described how the US and its allies exploited other nations' gullibility for years, taking their money and stealing their secrets.

The company specialised in communications and information security and was founded in the 1940s as an independent firm.

The CIA and the National Security Agency (NSA) spied on allies and adversaries alike through Crypto AG specialising in making cryptography equipment, the report said.

For more than half a century, governments all over the world trusted the Swiss firm to keep the communications of their spies, soldiers and diplomats secret, the Post said.

The company had clients such as Iran, military juntas in Latin America, India, Pakistan and even the Vatican, it said.

There was no immediate official reaction from New Delhi.

However, none of its customers ever knew that the Swiss firm was secretly owned by the CIA in a highly classified partnership with West German intelligence. These spy agencies rigged the company's devices so they could easily break the codes that countries used to send encrypted messages, according to the report.

'It was the intelligence coup of the century. Foreign governments were paying good money to the US and West Germany for the privilege of having their most secret communications read by at least two (and possibly as many as five or six) foreign countries,' the CIA report reads, according to the Post.