By Tom Wilson and Rae Wee

LONDON/SINGAPORE, May 27 (Reuters) - World shares gained on Tuesday as investors weighed up the latest tariff-related news, while long-dated U.S. Treasury yields were set for their biggest one-day fall since mid-April, mirroring a steep price rally in super-long Japanese debt.

After a weekend call with the European Commission's president, U.S. President Donald Trump paused until July 9 his threatened tariff of 50% on goods entering the United States from the European Union.

European shares .STOXX added 0.4%, supported by defence stocks, with UK shares .FTSE gaining 1% following a holiday at the start of the week.

Wall Street shares, which also saw no trade on Monday due to a U.S. holiday, were set for solid gains too, futures gauges ESc1 showed.

"Markets are getting more accustomed to Trump's threats and now partly assume the full threat won't immediately materialise," Deutsche Bank analysts wrote. "There is certainly fear fatigue."

Meanwhile, the yield on 30-year U.S. Treasuries US30YT=RR, which affect anything from U.S. government borrowing costs to home mortgage rates, fell 8 basis points to 4.9572%, their lowest in a week.

The 30-year yields - at the epicentre of the market sell-off in April following Trump's initial raft of tariffs - are still just below 5%, near their highest since October 2023.

The move mirrored a near-20 basis point fall in yields for Japanese 30-year debt JP30YTN=JBTC that came after a Reuters report on Tuesday that Tokyo will consider trimming issuance of the super-long bonds, after recent sharp rises in yields.

"Debt sustainability is again creeping into investors minds" regarding heavily indebted Japan, said Carsten Brzeski, global head of macro for ING Research. "That is a spillover from the concerns about the U.S."

A major focus for investors this week will be results from Nvidia NVDA.O on Wednesday, where the AI bellwether is expected to report a 66% jump in first-quarter revenue.

Speeches from a slew of Federal Reserve policymakers and Friday's U.S. core PCE price index are also due, which could provide clues on the outlook for U.S. rates.

In Asia, MSCI's broadest index of Asia-Pacific shares outside Japan .MIAPJ0000PUS fell 0.4%, although Hong Kong's Hang Seng Index .HSI outperformed with a gain of 0.4%.

LOSS OF CONFIDENCE

The dollar edged up 0.4% against a basket of currencies =USD but was still heading for a fifth straight month of declines, which would mark its longest such losing streak since 2017.

The euro EUR=EBS fell 0.3%, hovering near a one-month high at $1.13549, while the yen JPY=EBS weakened 0.6% to 143.71 per dollar.

Trump's flip-flops on tariffs and concerns over the worsening U.S. deficit outlook have undermined sentiment towards U.S. assets and in turn been a drag on the dollar.

"A U.S. dollar regime change could be in the making in the long term after it appears to have peaked recently," said David Meier, an economist at Julius Baer.

"Erratic U.S. policymaking, the tense fiscal situation, and large external indebtedness, against the backdrop of the twin deficit, suggest that a weaker USD is the route of least resistance."

And as the dollar loses some of its safe-haven appeal, investors have instead sought alternatives such as gold, sending prices to record highs this year XAU=.

Still, gold fell 1% to $3,307.69 an ounce as the dollar firmed. GOL/

Oil prices were little changed on increasing expectations that members of OPEC+ will decide to increase their output at a meeting later this week.

Brent crude futures LCOc1 fell 0.4% to $64.50 a barrel. U.S. West Texas Intermediate crude CLc1 fell the same amount to $61.26 a barrel.

(Reporting by Tom Wilson in London and Rae Wee in Singapore; Additional reporting by Dhara Ranasinghe; Editing by Saad Sayeed and Lincoln Feast.)

((Rae.Wee@thomsonreuters.com;))