0734 GMT - Singapore's retail sector could face significant headwinds in coming quarters, says UOB associate economist Jester Koh in a note. The city-state's retail sales activity rose by a modest 1.0% on month in June following a 2.2% contraction in May, driven by motor vehicle, supermarkets and food and alcohol sales, but other categories such as recreational goods remained subdued, he says. Intensifying headwinds to Singapore retail sales include lower international visitor arrivals and the diversion of resident spending abroad toward outbound travel, he says. Cautious household discretionary spending amid an uncertain labor market backdrop is also expected to weigh on the retail sector in coming months, he adds.