Iran's chief negotiator said on Tuesday that Washington must accept Tehran's latest peace plan or face failure, after US President Donald Trump warned the truce in the Middle East war was on the brink of collapse.
Both sides have refused to make concessions and repeatedly threatened to resume fighting, but neither appears willing to return to all-out war.
Traders are now looking to China, where Trump is due to land on Wednesday, the first visit by a US president in nearly a decade, saying he expected a "long talk" with counterpart Xi Jinping about Iran.
Trump's expected arrival in Beijing comes a day after figures back home in the United States showed consumer inflation hit a three-year high in April, as the economic fallout of the Iran war rippled through the world's largest economy.
Soaring inflation will pile pressure on Trump to end the war, which is deeply unpopular with the American public, but he insisted on Tuesday that Americans' financial situation did not motivate him "even a little bit" to make a peace deal with Iran.
The US president said he would ask Xi to "open up" China to American firms, adding that AI chip titan Nvidia's chief Jensen Huang was among a host of top CEOs joining the trip.
- Oil prices cool -
In Asian markets, Sydney, Taipei, Wellington, Manila, Jakarta and Kuala Lumpur were down, while Hong Kong, Shanghai, Mumbai, Bangkok and Singapore advanced.
London, Paris and Frankfurt were higher at the open.
Tokyo closed up 0.8 percent after the yield on 20-year Japanese government bonds hit its highest level since 1997.
Pressure on Japanese debt is intensifying as the Middle East war sends oil prices spiralling, fuelling speculation that the Bank of Japan will increase interest rates.
Traffic through the Strait of Hormuz -- through which one fifth of the world's oil supplies usually pass -- has virtually ground to a halt.
But oil prices cooled, with the international benchmark Brent crude falling 0.7 percent to nearly $107 a barrel, while US benchmark West Texas Intermediate also slipped 0.9 percent to $101 a barrel.
Seoul showed signs of recovery, climbing 2.6 percent after the presidential Blue House distanced itself from calls for a social tax on artificial intelligence profits.
The tech-rich Kospi had plunged five percent on Tuesday after a top official proposed a "national dividend" to redistribute excess corporate profits from artificial intelligence.
South Korea has said it will triple spending on AI this year, aiming to join the United States and China as one of the world's top three AI powers.
The collapse of Samsung Electronics' talks with its largest labour union dished another blow to Seoul's AI drive, with company shares falling as much as 6.1 percent, Bloomberg reported.
Samsung is a major producer of chips used in everything from artificial intelligence to consumer electronics, raising the prospect that a planned walkout could cause severe disruption and losses.
Delegations from China and the United States met for trade talks in South Korea, likely putting the finishing touches on any announcements for the Trump-Xi summit in Beijing.
- Key figures at around 0815 GMT -
Brent North Sea Crude: DOWN 0.7 percent at $106.98 a barrel
West Texas Intermediate: DOWN 0.9 percent at $101.28 a barrel
Tokyo - Nikkei 225: UP 0.8 percent at 63,272.11 (close)
Hong Kong - Hang Seng Index: UP 0.2 percent at 26,388.44 (close)
Shanghai - Composite: UP 0.7 percent at 4,242.57 (close)
London - FTSE 100: UP 0.7 percent at 10,337.93
New York - DOW: UP 0.1 percent at 49,760.56 points (close)
Euro/dollar: DOWN at $1.1710 from $1.1745 on Tuesday
Pound/dollar: DOWN at $1.3528 from $1.3542
Dollar/yen: UP at 157.79 from 157.57 yen
Euro/pound: DOWN at 86.56 pence from 86.70 pence
cms/mtp