Sparkling Rioja?

[Guilhaume gerard]

Few months ago, i was told about Pedro Pecina talking about how a lot of Rioja producers were sending Viura, Tempranillo blanco and other white grapes to the basque country to make Txakoli, as there is a revival of the wine and the demand grew a lot in the past 3/4 years.
I've tried to ask a few journalists and bloggers about it, but no one seems to care enough to investigate. Anyone ever heard about such practices?