* Urbi records loss of 1.338 billion pesos * Sales slump 85 percent to 468 million pesos MEXICO CITY, April 28 (Reuters) - Mexican homebuilder Urbi posted a 1.338 billion peso ($108.5 million) loss in the first quarter as sales collapsed, debt payments weighed and derivatives bets soured. Sales fell 85 percent to $468 million pesos from $3.066 billion in the year ago period, the company said in an e-mailed statement on Saturday. The company's official filing with the Mexican stock exchange was not yet available on Sunday. The quarterly loss compared to a profit of 563 million pesos in the same period last year. The company said financing costs surged and losses on derivatives positions more than doubled compared to last year in the first quarter to 921 million pesos. Urbi missed a bond coupon payment earlier this month, invoking a 30-day grace period. The company said it would receive a report from financial advisor Rothschild on a potential debt restructuring in the coming weeks. The company's stock, which sank to a record low at the end of last week, has fallen more than 90 percent in the last two years to close at 1.95 pesos on Friday.