LONDON, Aug 1 (Reuters) - Travis Perkins, Britain's biggest supplier of building materials, reported a 31% drop in first-half operating profit in "challenging" market conditions, and said its near-term trading was expected to remain difficult.

Chief Executive Nick Roberts said the difficult conditions were reflected in both the first-half performance and the outlook for the balance of the year. First half profit came in at 112 million pounds ($144 million).

"Whilst near-term trading is expected to remain difficult, we continue to work to position the group to benefit from the long-term structural drivers in our end markets," he said on Tuesday.

The company stuck to the full-year adjusted profit forecast of 240 million pounds it had downgraded in June after volumes in new build housing and renovation markets were hit by higher interest rates and weaker consumer confidence.

($1 = 0.7798 pounds) (Reporting by Paul Sandle; Editing by Kate Holton)