LONDON - Global ​stock markets faltered and oil prices were ⁠stuck above $100 a barrel on Friday, as fears of a renewed military escalation in the Middle East kept investors on edge heading into the ‌weekend.

European shares opened broadly lower, although Japan's blue-chip Nikkei gained almost 1%, and U.S. stock futures were a touch higher .

Oil prices, trading near $107, faced renewed upward pressure after Iran released footage ​of commandos boarding a cargo ship in the Strait of Hormuz and reports that Tehran's air defences had engaged "hostile targets".

Oil has jumped more than 17% this week, set for its biggest weekly ​rise ​since the first week of war in March - a sign that hopes for a swift end to the conflict are fading.

"The week has ended with an escalation after a de-escalation and that has taken the edge off sentiment," said Rory McPherson, chief market strategist at financial planning firm Wren ⁠Sterling.

While Iran has flaunted its tighter grip over the key Strait of Hormuz, U.S. President Donald Trump said he had ordered the Navy to "shoot and kill" Iranian boats laying mines in the waterway, and step up demining activity.

Trump's comments came just days after he said he would indefinitely extend what had been a two-week ceasefire with Iran to allow for further peace talks.

MSCI's world stock index was a touch lower on the day, but not too far from last week's record ​highs.

"We are aware that markets ‌had a strong run ⁠from the lows of March and ⁠we would focus on the fundamentals, which look strong," said McPherson.

"You have markets that are sensitive to oil, such as Europe and Japan and you have sectors such ​as semiconductors in the United States that are up strongly."

The S&P 500 tech index has rallied 16% so far ‌in April and is set for its best month since 2002.

Investors could be underestimating upside potential in ⁠stock markets with focus on the downside risks, given the uncertainty generated by the Iran war said Jim Caron, chief investment officer at the Portfolio Solutions Group at Morgan Stanley Investment Management.

"What I think people don't talk about enough are the positive aspects to the market and there's an upside tail risk as well," he said. "Earnings have been strong."

YEN ON THE CUSP OF 160

In currency markets, the dollar was on track for its first weekly gain in three on dampened hopes for an immediate easing of Middle East tension.

That left Japan's yen teetering near 160 to the dollar , and currency traders were uneasy about the prospect of intervention by Japanese authorities to bolster their currency.

Japanese Finance Minister Satsuki Katayama reiterated a verbal warning on intervention, saying authorities could take "decisive" action against speculative moves in the foreign exchange market, a day after saying Japan had a "free hand" to intervene and that past interventions had been effective.

The euro ‌was little changed on the day at $1.1684, while sterling was slightly firmer, at $1.3473.

Major central banks such as ⁠the U.S. Federal Reserve, the European Central Bank and the Bank of England, meet next week, with investors ​awaiting policymakers' comments on the war's impact on inflation and the economy.

The Bank of Japan (BOJ) also meets next week, but expectations are for the central bank to keep rates on hold.

"Lower market liquidity during Golden Week, which comes directly after the BOJ meeting, may provide an opportunity for FX intervention and a knee-jerk appreciation in the yen within the ​150–160 range," said ‌Carl Ang, fixed income research analyst at MFS Investment Management.

The annual Golden Week holiday, during which markets will be closed on ⁠a number of days, runs into early May.

Elsewhere, spot ​gold was down just 0.1% to $4,688 an ounce.

(Reporting by Dhara Ranasinghe in London and Rae Wee in Singapore, Editing by Clarence Fernandez)