* May trade balance surprise on upside
* High oil prices, weaker foreign demand key risks
By Martin Santa
BRATISLAVA, July 11 (Reuters) - Slovakia's foreign trade balance posted a surprise surplus in May, data showed on Friday, but analysts said further improvement would depend on world oil prices and foreign demand.
Foreign trade balance showed a 4.1 billion crown ($213.4 million) surplus, compared with a revised deficit of 6.8 billion in April, the Statistics Office said [
].Foreign trade, key for economic growth in central Europe has remained strong, data from Hungary [
] and Czech Republic [ ] showed in the past days, but analysts say the flagging western European eocnomy and surging currencies would take their toll in the coming months."The general outlook for trade balance in our view looks less positive," said Piotr Matys, analyst with 4Cast in London.
"We've expected exports growth to be fuelled by car manufacturing, but we see downside risk for demand for new cars across Europe as economies are slowing down," added Matys.
Industrial output growth slowed in May as production in the country's dominating car and machinery sector lagged expectations, data showed on Tuesday, but analysts said it should pick up again next month [
].High oil prices -- U.S. crude <CLc1> rose $1.18 to $142.82 a barrel early on Friday after jumping $5.60 on Thursday on geopolitical and supply fear -- were negatively influencing trade balance since the beginning of the year.
"Oil prices deliver a monthly burden of five billion crowns on imports," said Juraj Valachy, analyst with Tatra Banka.
"The import side of the trade balance was negatively affected by high oil prices in the first four months of the year as oil prices surged even when the crown appreciation is taken into account," said Maria Valachyova, Slovenska Sporitelna senior analyst.
The Statistics Office said overall imports of energy goods, as well as imports for the electronics sector, fell on the month in May.
U.S. crude prices rose by 96.8 percent on the year in May, trading at $143.45 a barrel as of 0825 GMT, while the crown firmed by 24.3 percent on the year against the dollar, trading at 19.170 <SKK=> against the greenback as of 0825 GMT.
The crown currency has been driven, in the past few months, by market expectations of a strong conversion rate against the euro when entering the single currency area next January. The final switchover rate was set at 30.1260 per euro on Tuesday.
The car sector, centred on assembly plants of Volkswagen <VOWG.DE>, PSA Peugeot Citroen <PEUP.PA> and Kia Motors Corp. <000270.KS>, and electronics giants Sony <6758.T> and Samsung Electronics <005930.KS> are Slovakia's economic backbone.
(Editing by Victoria Main)