Bucher's overall nine-month orders dropped nearly 7 percent to 1.7 billion Swiss francs ($1.7 billion), when adjusted for currency and acquisitions, the company said on Thursday. Sales slipped 7 percent to 1.8 billion francs.

But municipal vehicle orders plunged 15.6 percent to 261 million francs, driven lower by "a noticeable impact on demand in the important British market for sweepers and sewer cleaners" following the June 23 Brexit vote, a spokesman said.

London's streets are among those tidied up by Bucher sweepers, many of which are made at its factory in Dorking, Surrey in the south of England.

Bucher is also feeling the effect through its newly acquired Danish business, J. Hvidtved Larsen A/S, which manufactures truck-mounted sewer-cleaning units and makes about half its annual sales in the UK.

Sterling's post-Brexit slide against the euro and Europe's other currencies has raised import costs, making British buyers reluctant to invest in new equipment, Bucher said.

The orders trend has continued, leaving the Swiss company anticipating weaker UK sales in the fourth-quarter, too.

Bucher shares on Thursday fell as much as 6.6 percent in Zurich before recovering some of the decline. The stock was trading 5.5 percent lower at 1430 GMT.

Other factors affecting Bucher's vehicle orders have been weak winter maintenance business, a large 2015 Russian order that was not repeated and weak garbage truck demand from Australia.

Bucher, whose separate agriculture equipment unit has been hurt by low commodities prices in particular in North America, now expects a downturn in full-year sales and a significant fall in operating profit and group profit margins.

($1 = 0.9926 Swiss francs)

(Editing by Alexander Smith)

By John Miller