UPDATE 1-UK homebuilder Crest Nicholson hit by flat prices, rising costs

(Adds details on results, executive comment)

June 11 (Reuters) - Crest Nicholson Holdings Plc reported a fall in pretax-profit for the first half of 2019 as Brexit nerves kept house prices flat across the south of England and building costs continued to climb.

Crest, which builds houses and flats in London and across England's southern half, said forward sales were up 15% in the first half, leading it to stick to its previous forecast for the full year.

Revenue rose 7% to 501.9 million pounds for the six months ended April 30, but the rise in costs drove pretax profit 11% lower to 64.4 million pounds.

Interim Chief Executive Officer Chris Tinker said in a statement the rise in forward sales had also come at the cost of slightly lower margins.

"Together with generally flat pricing and continuing build cost inflation, (that) has contributed to a reduction in the operating margin," he said.

(Reporting by Samantha Machado in Bengaluru; editing by Patrick Graham)