Brent crude futures rose nearly 20% at one point in their biggest intra-day gain since the Gulf War in 1991, and U.S. futures jumped almost 16%, both hitting their highest level since May. But prices came off their peaks after U.S. President Donald Trump authorised the use of the country's emergency stockpile to ensure stable supply.
By 0823 GMT, Brent futures were up 8.75% at $65.49 per barrel, while U.S. light crude was up 7.8% at $59.13.
The upheaval in the oil market and poor economic data from China bolstered investors' demand for safe-haven assets, pushing the Japanese yen and Swiss franc higher and sending core euro zone bond yields lower.
World stocks halted a four day winning streak and were down 0.16%. European shares fell 0.55% and Wall Street signalled a weak start, too, with E-Mini futures for the S&P 500 off 0.34%.
The surge in crude prices comes at a time when central banks in the United States, Europe and Asia are easing monetary policy to fight a slowdown in the global economy amid a drawn out trade war between Washington and Beijing.
"Spikes in oil prices when the global economy is already flirting with the idea of recession is not ideal and, if repeated and sustained, could ultimately be what tips us over the edge," said Craig Erlam, analyst at OANDA in London.
Data from China further underscored worries about the slowdown in the world's No. 2 economy. Industrial production grew at its weakest pace in 17-1/2 years amid rising U.S. trade pressure and softening domestic demand.
Trump also said the United States was "locked and loaded" for a potential response to the strikes on the Saudi facilities, after a senior official in his administration said Iran was to blame.
That inflamed fears about Middle East tensions and worsening relations between Iran and the United States, powering safe-haven assets, with gold up 0.92% to $1,502.1 per ounce.
"The bigger issue is what premium markets will build in to reflect the risk of further attacks," said Kerry Craig, Global Market Strategist, J.P. Morgan Asset Management.
"In the very near-term, we may also see a pick-up in safe-havens," he added.
"Central banks are likely to look through the inflationary impact of higher oil prices but the added geopolitical risk to an already fragile backdrop will not go without notice."
The U.S. Federal Reserve is due to hold its policy meeting on Wednesday, at which it is widely expected to ease interest rates and signal its future policy path.
SAUDI BONDS HIT
Dollar-denominated bonds issued by Saudi Arabia's government and state-oil firm Saudi Aramco tumbled to multi-week following the attacks.
Saudi Aramco's longer-dated bonds bore the brunt of the falls with the 2049 issue dropping nearly 3 cents in the dollar to touch their lowest since early August, data from Tradeweb showed.
"Markets had become too sanguine over the last few months about the geopolitical risks facing countries allied with the US against Iran, with Saudi Arabia particularly vulnerable," said Patrick Wacker at UOB Asset Management.
"While Saudi Arabia's sovereign fundamentals are still firm, bond prices will need to factor in higher geopolitical risk going forward," he added.
In currency markets, the Saudi news pushed the yen up 0.2% to 107.88 per dollar, while boosting currencies of oil-exporting countries.
The Norwegian crown surged as much as 0.7%, then settled at 8.9517 crowns against the dollar, up 0.37% on the day, while the Canadian dollar rose 0.23% to C$ 1.3253. The Russian rouble was also higher.
The currencies of oil importers such as Turkey and India underperformed.
The U.S. dollar was little changed against a basket of currencies.
Elsewhere in bond markets, core longer-dated euro zone bond yields edged lower as the and the poor data from China bolstered demand for safe-haven assets.
Germany's 10-year benchmark was down 1 bp at -0.46%. Bund futures rose 0.12%, while Futures for U.S. 10-year Treasury notes rose 0.27%.