Volkswagen's Czech unit Skoda Auto plans to shift production of some high-earning models to other VW group plants in other countries, the carmaker's trade union boss said in an article on Thursday.

A Skoda spokeswoman declined to comment.

Skoda is the central European country's biggest exporter, but its success has sometimes caused friction within Volkswagen, whose labour boss has accused it of cannibalising sales.

Jaroslav Povsik, Skoda's trade union chairman and supervisory board member, said the company planned to move production of the luxury Skoda Superb and SUV Skoda Kodiaq to Slovakia and Germany respectively, while another SUV, Seat brand's Ateca, was set to go to Spain.

"Isn't this campaign against Skoda enough? Do we have to strip Skoda of all that is good and excellent that we have now?" Povsik said in a front-page article in the union's weekly bulletin, Skodovacky Odborar.

"We will fight on all fronts - in the press, with the government, via the public, at Volkswagen, everywhere," he said.

Last year, Skoda made 29,298 Superbs, 101,586 Kodiaqs and 98,370 Seat Atecas at its plants in the Czech Republic.

Globally, the company delivered 1.24 million cars in 2019, with China and Germany as its top markets. Like other carmakers, Skoda is battling to get back from shutdowns due to the coronavirus crisis and now faces uncertainty over demand.

Volkswagen group Chief Executive Herbert Diess told Frankfurter Allgemeine Zeitung (FAZ) in July that Skoda - one of VW's 12 brands - needed to do more to compete with South Korean and French rivals.