A secretive unit inside Mexico's predominant television network set up and funded a campaign for Enrique Peña Nieto, who is the favourite to win Sunday's presidential election, according to people familiar with the operation and documents seen by the Guardian.

The new revelations of bias within Televisa, the world's biggest Spanish-language broadcaster, challenge the company's claim to be politically impartial as well as Peña Nieto's insistence that he never had a special relationship with Televisa.

The unit - known as "team Handcock", in what sources say was a Televisa codename for the politician and his allies - commissioned videos promoting the candidate and his PRI party and rubbishing the party's rivals in 2009. The documents suggest the team distributed the videos to thousands of email addresses, and pushed them on Facebook and YouTube, where some of them can still be seen.

The nature of the relationship between Peña Nieto and Televisa has been a key issue in Sunday's election since the development in May of a student movement focused on perceived media manipulation of public opinion in the candidate's favour.

Remember that Mexico is a market in which TV commands an outsized portion of the market for political coverage.  Paper readership is fairly low and online media has a low penetration rate.  Controlling the majority of TV coverage is a huge advantage.  

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg