While Cupra's lineup is being expanded, the Seat brand will not get any new product in the short-to-medium term, and there is currently no plan to give it a battery-electric model, which has raised doubts about its future.
Griffiths said Cupra will not replace Seat because it's positioned in a different part of the market.
"The Seat brand has never been stronger," he said.
"With the combustion engine cars and the plug-in hybrids, the Seat brand has a good medium-term future," Griffiths said.
"In the longer term, however, we have to prioritize our investments. We have seen that electric cars will go to the market starting from premium brands, so it was clear that we have a better opportunity of electrifying Cupra. Both brands make a lot of sense, at least until the end of this decade," Griffiths said.
Last year Cupra accounted for 17 percent of Seat's vehicle sales volumes but close to 25 percent of revenues, and its share of profits was even larger, Griffiths said.
This year Seat aims plan to double Cupra's vehicle sales depending on the availability of semiconductors and other components, he said.
Seat had an operating loss of 371 million euros ($407 million) in 2021, when production was 25 percent less than planned because of a lack of chips.
Seat and Cupra sold 60,000 plug-in hybrids in 2021, four times the 14,700 sold the previous year.
Still, Seat had to pay a fine for exceeding its fleet CO2 target set by the European Union to help reduce greenhouse gas emissions.
The penalty was "a single-digit figure" in 2021, down from 260 million euros in 2020.