The former intelligence analyst Edward Snowden has broken his silence.

Reuters news agency says its seen a letter written by Mr Snowden to Ecuador saying that the United States was illegally persecuting him for revealing its electronic surveillance programme, PRISM.

"No matter how many more days my life contains, I remain dedicated to the fight for justice in this unequal world. If any of those days ahead realize a contribution to the common good, the world will have the principles of Ecuador to thank," part of the text read, according to a translation.

He also thanked Ecuador for helping him get to Russia and for examining his asylum request.

Mr Snowden is also believed to have asserted that he is free to publish information that serves the public interest.

Earlier it was reported that the US whistleblower has applied for political asylum in Russia.

Its been eight days since since the 30 year old fled to Moscow - he is currently situated in a transit area of Moscow airport.