* Early indication of small impact on economy: central bank chief
* PM Lee says region should stay open for trade - media
* Economists say tourism, retail could be affected
* Singapore has narrowed economic growth for year (Updates with latest Zika toll and PM Lee comments)
By Marius Zaharia and Anshuman Daga
SINGAPORE, Sept 6 (Reuters) - A Zika outbreak in Singapore could have a small impact on the almost $300 billion economy, the central bank chief said on Tuesday, as the mosquito-borne virus spreads across the global financial and transit hub.
Ravi Menon, managing director of the Monetary Authority of Singapore, did not give further details, but the outbreak coincides with a dip in overall exports and growth in the trade-dependent economy. Growth is also slowing in China, Singapore's main overseas market.
"It's too early to tell. I would say early indications are there could be some small impact, but it's not likely to be significant from an overall economy outcome," Menon told reporters when asked about the impact of Zika.
"But really, it's still early days," he said at an event hosted by the Foreign Correspondents Association in Singapore.
Small, tropical Singapore reported its first locally infected Zika patient on Aug. 27 and since then, the number of reported infections has reached 275, with 17 more cases reported on Tuesday.
Health officials say the figure will rise, as the Aedes mosquitoes that carry the virus are all over the island, and hospitals have stopped isolating patients.
Prime Minister Lee Hsien Loong was quoted on the Channel News Asia website as calling at a regional summit in Laos for the 10 Southeast Asian countries to "join hands" to fight Zika, while keeping the region open for business and trade.
"It is imperative for us to work together to combat Zika, but we should put Zika in the proper context," Lee said. "Given the presence of the Aedes mosquito, Zika may become endemic in our region, just like dengue."
"We should prepare ourselves for a possibly extended campaign against Zika but ensure that the region remains open and connected for business and trade."
Last month, Singapore narrowed its economic growth forecast for the year to 1-2 percent from 1-3 percent growth previously expected, citing concerns over Brexit and weak global demand.
Economists said tourism and retail would be the areas most affected by Zika, which could in turn hold back growth. Tourism arrivals in the first six months of the year have increased 12.5 percent from a year ago, official statistics show.
"Tourism is about voluntary trips and this is going to have a dent," said Trinh Nguyen, senior economist for emerging-market Asia at French investment bank Natixis SA in Hong Kong.
"Zika will impact sentiment and people's already low propensity to consume."
Retail sales excluding motor vehicles fell year-on-year in June for the fifth straight month, as worries about the sluggish global economy drove Singaporeans to cut spending.
Singapore is due to host a Formula One motor-racing Grand Prix next week. Promoters of the race say preparations are going on as usual. The Tourism Board says Singapore remains a safe destination.
Chan Brothers Travel, one of Singapore's biggest travel agencies, told Reuters there had been no cancellations but new bookings may slow down.
While most people experience mild symptoms, Zika infections in pregnant women have been shown to cause microcephaly, a severe birth defect in which the head and brain are undersized. In adults, it can cause a rare neurological syndrome called Guillain-Barre.
Zika is also affecting large parts of Latin America and the Caribbean, with Brazil the hardest hit. In Southeast Asia, Malaysia, the Philippines and Thailand have also reported Zika infections.
Regional health experts said a lack of adequate testing meant the spread of Zika was likely significantly under-reported. (Additional reporting by Masayuki Kitano, Fathin Ungku and Saeed Azhar; Editing by Miral Fahmy, Robert Birsel)