Sweett warned profits for 2015 will be materially below market expectations due to challenges in overseas business, in Asia and the Middle East, and also revealed there will be a material charge for costs relating to an investigation into bribery allegations made last year.
The Wall Street Journal in 2013 alleged that an ex-employee requested a bribe for £64.7mln to complete a deal.
Sweett today said the current phase of an independent investigation is nearing completion, and it continues to cooperate with the Serious Fraud Office (SFO). The company commissioned probe was launched in April.
In terms of its trading performance this year Sweett said there was good progress for UK based business in the six months to September 30, but overseas business was mixed.
It added that a review of the group’s operations identified challenges in certain overseas operations.
"Since becoming chairman in August, I have conducted a thorough review of the Group's business, the outcome of which is set out in today's announcement,” said chairman John Dodds.
“I am looking forward to taking the business forward with a greater focus on profitability and cashflow."
An interim results statement for the six month period is due on December 2.
On AIM, Sweett shares were down 9.5p, 27.94%, trading at 24.5p – though in early deals a low of 20.25p was seen.