Main oil contract Brent North Sea surged toward US$100 a barrel on Thursday (Jul 23) as Tehran-backed Houthi rebels targeted Red Sea shipping, raising fears that the Middle East war is widening. Most Asian stock markets were buoyed by a much-needed bounce for regional tech firms as investor appetite for artificial intelligence (AI) seesaws. European markets were weaker, with London, Paris and Frankfurt all falling in midday trading.The dollar firmed against its main rivals. International oil benchmark Brent soared as much as 5 per cent to above US$98 a barrel after Houthi rebels claimed to have struck two Saudi oil tankers in the Red Sea. Iran vowed to keep striking the region so long as it remains under attack by US strikes."Investors are in a wary mood ... as fresh jitters of worry about the ongoing energy crunch hit sentiment," said Susannah Streeter, chief investment strategist at Wealth Club."With both the Strait of Hormuz and the Red Sea now under increasing pressure, markets are bracing for the possibility that the conflict could disrupt key energy routes, (and) keep oil prices elevated," she added.The prospect of higher oil prices also raises the prospect of higher inflation and interest-rate hikes, adding to weak sentiment, analysts said.London's FTSE 100 index was dragged into the red by a 9 per cent drop in Centrica shares as the owner of British Gas laid out plans to cut 1,300 jobs alongside a mixed earnings update.Paris shed 1 per cent, weighed down by a 15 per cent drop in semiconductor group STMicroelectronics as its sales forecasts fell short of expectations. French oil and gas giant TotalEnergies jumped 3 per cent after reporting that net profit doubled in the second quarter as the war pushed up energy prices.Asian traders bought back into beaten-down tech stocks, with Seoul up more than 4 per cent, helped by rallies in chip giants SK hynix and Samsung, while Tokyo was boosted by Advantest and SoftBank.Hong Kong and Shanghai also rose. Investors' appetite for all things AI has been tested in recent months on concern about elevated valuations and as they question when the trillions pumped into the sector will see returns.An earnings report from Google-parent Alphabet on Wednesday raised fresh concerns as it said it would likely spend as much as $205 billion on AI this year, far more than expected. Next week's results from Microsoft, Meta and Amazon will be pored over for their capital spending plans.Eyes are on Tokyo after the yen hit a fresh four-decade low against the dollar amid concerns over the gap between the Bank of Japan's low interest rates and those in the United States and other big economies.Rising oil prices and concerns over Japan's economy have added to pressure on the currency.