* Brent crude stays near $75 on worries U.S. may exit nuclear deal
* Dollar surges to new 2018 high on relative strength of US growth
* Resilient tech sector underpins world shares after two days of gains
By Sujata Rao
LONDON, May 8 (Reuters) - Oil prices eased on Tuesday from 3-1/2-year highs hit on worries the United States may be set to pull out of a key nuclear accord with Iran, while robust tech sector gains in Asia helped support world stocks.
U.S. President Donald Trump will announce at 1800 GMT whether Washington will withdraw from a deal that eased economic sanctions on Iran in exchange for Tehran limiting its nuclear programme. A decision to leave the accord could give another boost to this year's 13 percent oil rally, by constraining Iranian crude exports.
Brent futures nevertheless eased 0.8 percent after hitting new highs above $75 a barrel and MSCI's world equity index inched a touch higher after two days of gains and having touched one-week highs in the previous session.
"(Trump's decision) has been so well covered, it's probably all in the price by now. And most recent commentary seems to be that after all the bluster, he may only partially withdraw from the deal," said Frances Hudson, global thematic strategist at Aberdeen Standard Investments.
She noted that oil prices had bucked a recent rise in the dollar -- usually the two are inversely correlated -- suggesting investors remained optimistic about the world economy and hence future demand for crude.
The dollar surged to a new 2018 high versus a basket of currencies.
"It's telling you that people are still in glass-half-full mode as far as the economy is concerned and despite the recent weak data in Europe. Growth remains on a an even keel in most places," Hudson added.
Wall Street was lifted on Monday by a strong rally in Apple shares to new record highs following forecast-beating results last week and Warren Buffett's decision to increase his stake in the firm.
MSCI's global tech index closed Monday at six-week highs and the gains fed into Asian tech companies, boosting emerging Asian shares by 0.5 percent and Japan's Nikkei index by 0.2 percent.
Momentum fizzled in Europe, however, with a pan-European index trading flat and Europe's tech index down 0.2 percent.
Italian shares slipped 1.5 percent, albeit from nine-year highs as chances grew of new elections following an inconclusive March 4 vote.
Equity futures signalled a weaker open for Wall Street .
ASI's Hudson also played down fears that a fresh oil price rise could further stoke global worries about inflation and growth, especially after some multinational companies warned that rising input costs could dent future profits.
"I don't think energy costs for many companies these days are a big enough proportion of their cost base, especially for tech and service sector shares," she said, noting the tech sector's resilience.
There was some good news from China as Beijing reported that April exports and imports had beaten forecasts. Trade tensions between China and the United States also seem to have abated slightly, with talks set to resume next week.
That helped lift China's blue-chip CSI300 index 1.3 percent.
In currency markets, the prospect of solid U.S. economic growth, helped by Trump's tax cuts and spending, propelled the dollar to a new 2018 high against a basket of currencies.
The greenback is being supported by expectations of further rises in U.S. interest rates, which are prompting investors to buy back dollars they had sold earlier this year on worries about Trump's protectionist trade policies.
"For the foreseeable future attractive interest rates at favourable risk conditions will only be on offer in the United States," Commerzbank analysts said, referring to the fading likelihood of policy tightening in Europe and Japan.
The euro fell 0.3 percent against the dollar to $1.1977 , the lowest since end-December.
The dollar gains have rippled through foreign exchange markets in recent days, prompting investors to unwind some of this year's best performing trades, especially in emerging markets.
The combination of higher oil prices, a strong dollar and higher U.S. rates is risky for some emerging market assets as it could significantly worsen their trade balance and possibly make it harder to service dollar-denominated debt.
JPMorgan's index of sovereign emerging dollar debt saw spreads over Treasuries surge to the highest since early-2017 while currencies such as the Indian rupee and Indonesian rupiah fell to multi-month lows.
The Turkish lira plumbed a new record low while Argentina, possibly the hardest hit by recent dollar turnaround, has been forced to raise interest rates to 40 percent to stem the bleeding in its peso
Additional reporting by Hideyuki Sano in Tokyo and Andrew Galbraith in Shanghai; Editing by Catherine Evans