It said 20 projects worth more than £315m had been deferred, noting that its construction order book had fallen in value from £2bn to £1.8bn in the past six months.
WSP said pre-tax profit for the year to 31 December would not be less than £12m, £3.1m down on last year. WSP said: "Since the announcement of our interim results at the beginning of September we have experienced a continuing softening of the market, particularly in the private and commercial sectors in the UK, Sweden and the Far East." The firm's interim results showed a 1.6% increase in pre-tax profit.
A senior city analyst said that although Amec's Canadian engineering subsidiary Agra was performing poorly the rest of the business remained strong. He said: "The group is broadly based – three-quarters of it is trading well."
Amec also announced that it is to exercise an option to acquire 54% of French firm Spie for £172m. Amec chief executive Sir Peter Mason said: "This acquisition marks the five-year transformation of the company into a truly international engineering services group."