UPDATE 1-Hire firm Ashtead warns on 2009-10 profits

* Q4 rental revenues drop 24 pct year-on-year

* 2008-9 profits seen towards lower end of forecasts (Adds detail)

LONDON May 11 (Reuters) - British equipment hire firm Ashtead (AHT.L) warned on Monday that profits for 2009-10 were likely to fall below its expectations due to a slump in private-sector construction markets.

The group, which rents out a range of industrial equipment from diggers to small tools, said fourth-quarter rental revenues at constant exchange rates dropped 24 percent compared with the same time last year.

Underlying profits for the year ended April 30 were likely to be towards the lower end of analysts' forecast range of 85.5 million to 95.4 million pounds ($125-140 million), it added.

That would be down from 112.3 million pounds the year before.

Ashtead did not give a forecast for 2009-10 underlying profit.

According to Reuters Estimates, the average forecast of nine analysts is 59 million pounds, although estimates range from 49 million to 80 million pounds. (Reporting by Mark Potter; Editing by Rupert Winchester)