Oct 12 (Reuters) - UK building materials supplier SIG cut its full-year operating profit forecast on Thursday amid softer demand and "challenging" market conditions.

"Market conditions remain challenging, with a further softening in demand in September, most notably in new build residential segments across all geographies," the company said in its third-quarter trading statement.

The Sheffield-based company, which sells roofing and insulation materials in Britain and some other European countries, said it expects weaker demand conditions to persist through the rest of the year.

Britain's housing market has been battling a slowdown for most parts of this year as high mortgage rates dampen demand and weigh on new construction, and the situation is almost similar in many European markets as well.

SIG now expects its annual underlying operating profit in the range of 50 million pounds to 55 million pounds ($61.6 million-$67.7 million), below the lower end of the market view of 65.3 million pounds-84 million pounds range guided in July.

($1 = 0.8120 pounds) (Reporting by Aby Jose Koilparambil in Bengaluru; Editing by Subhranshu Sahu)