Oil futures rocketed more than 13 percent at one point, reaching the highest levels since January and reigniting worries about a renewed spike to inflation.

Fears of a higher-cost environment sent share prices sliding for a majority of companies across Asia and Europe.

Energy majors jumped, however, as despite a pullback heading into the Wall Street open, crude was still up by around 8.5 percent.

The dollar jumped, while gold -- viewed as a safe haven investment -- was close to its record high of above $3,500 an ounce set in April.

"Global markets are being rattled by an escalation of Middle East tensions," noted Richard Hunter, head of markets at trading group Interactive Investor.

"Asian markets were the first to react to the news overnight, with (stock market) declines across the board."

Europe followed suit, with almost all the continent's stock indices in negative territory nearing the half-way stage.

Iran called Israel's wave of strikes a "declaration of war", after the Israeli military hit about 100 targets including nuclear facilities and killed senior figures, among them military chiefs and top nuclear scientists.

US President Donald Trump told Fox News he had prior knowledge of the Israeli strikes, which Israel said involved 200 fighter jets.

Trump also stressed that Tehran "cannot have a nuclear bomb".

Iran's supreme leader Ayatollah Ali Khamenei warned Israel it faced a "bitter and painful" fate over the attacks, while the Iranian military said there were "no limits" to its response.

"The big fear for investors is that an escalation to the tensions will not only raise the risk of a prolonged conflict, but it could disrupt Iranian oil production," said Matthew Ryan, head of market strategy at global financial-services firm Ebury.

"We suspect that safe haven assets will be well supported in the coming days, as markets brace for additional retaliatory attacks and the possibility of a wider conflict."

Ryan added in a client note that "the spike in oil prices... has broader implications, as it could both weigh on the global growth outlook and keep inflationary pressures higher for longer, which complicates the easing cycle among the world's major central banks".

- Key figures at around 1045 GMT -

Brent North Sea Crude: UP 8.3 percent at $75.13 per barrel

West Texas Intermediate: UP 8.7 percent at $73.98 per barrel

London - FTSE 100: DOWN 0.4 percent at 8,846.17 points

Paris - CAC 40: DOWN 1.2 percent at 7,671.99

Frankfurt - DAX: DOWN 1.5 percent at 23,414.13

Tokyo - Nikkei 225: DOWN 0.9 percent at 37,834.25 (close)

Hong Kong - Hang Seng Index: DOWN 0.6 percent at 23,892.56 (close)

Shanghai - Composite: DOWN 0.8 percent at 3,377.00 (close)

New York - Dow: UP 0.2 percent at 42,967.62 (close)

Euro/dollar: DOWN at $1.1502 from $1.1583 on Thursday

Pound/dollar: DOWN at $1.3526 from $1.3605

Dollar/yen: UP at 144.36 yen from 143.56 yen

Euro/pound: DOWN at 84.95 pence from 85.11 pence

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J.P. MORGAN CHASE & CO

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