The manufacturer builds its medium-sized van, the Vivaro, at Luton before supplying the vehicles to the UK and other European markets.
Ellesmere Port produces the Astra passenger car for UK and European markets.
Vauxhall said the downturn in sales across Europe meant supply was outstripping demand and that closing the facilities for a working week was more efficient than shutting the plants for occasional days.
Staff at the factories are to be paid as normal with hours banked for when there is an upturn in demand.
Vauxhall said the move to suspend production represented normal working practice to match supply with demand rather than building up too much stock.
The Luton plant, which will produce the next generation Vivaro from 2014, has a 1100-strong workforce.
