According to the latest figures released by the Society of Motor Manufacturers and Traders (SMMT), the number of commercial vehicles manufactured fell 32.2% to 5,127 last month, compared to May 2013.
The number of commercial vehicles produced for the export market witnessed a particularly sharp fall year-on-year of 43.8% from 3,898 to 2,190, the domestic market faring little better with a 19.8% fall from 3,662 to 2,937.
Year-to-date, production fell 22.8% from 40,037 to 30,917 overall, with both the home and export markets witnessing similar decreases of 24.1% and 21.4% to 15,349 and 15,568 respectively.
Mike Hawes, chief executive of SMMT, said the figures were symptomatic of the continued effect of production restructuring last year, and reassured: "There is light at the end of the tunnel, however, as we look forward to the end of this impact in late summer."
He added: "The next few months will also see new models rolling off UK assembly lines, which will help boost production numbers."