The decline returns the market to the negative pattern set in the first four months of the year, which was broken when sales went up 6.7% in May.
In the first six months of the year new van volumes were down by more than 10% to 119,786 compared to the corresponding period in 2011.
SMMT boss Paul Everitt said that while the commercial vehicle market is generally stable “it is far from settled”.
He predicted the sector would be heavily influenced by the state of the economies in the UK and Europe as a whole during the second half of the year.
Despite the drop in the market overall, sales in the largest sector, heavy vans, grew by 8% to 13,323 units in June.
Vauxhall endured a particularly torrid month. Normally a fixture in the top three sellers list with Ford and VW, it saw registrations plummet by 35% and was overtaken by both Mercedes and Renault.
