China markets flat, Hong Kong dips as initial trade optimism wanes

• Investors remain cautious, fret over lack of details
• Onshore market trades sideways, Hang Seng slips from 3-month high
• Tech shares lead losses with chip curbs unaddressed

HONG KONG, June 12 (Reuters) - Chinese stocks steadied after an initial fall and Hong Kong shares were trading lower on Thursday, led by declines in the tech sector, as markets struggled to sustain positive momentum from Sino-U.S. trade talks that provided few concrete details.

A trade truce between the world's two biggest economies was back on track, according to U.S President Donald Trump, a day after negotiators from Washington and Beijing agreed on a framework to ease bilateral retaliatory tariffs.

Under the agreement, Beijing will lift export restrictions on rare earths minerals while the U.S. will restore Chinese students' access to its universities, Trump said on Truth Social.

Yet the terms remain subject to final approvals with details notably absent. The 55% tariffs on Chinese imports will also remain unchanged, U.S. Commerce Secretary Howard Lutnick said.

"We still don't know if what Trump says will actually happen. It's disappointing that the tariffs rates was not dialled down at all and tech curbs on China was not even mentioned," said Jason Chan, senior investment strategist at Bank of East Asia, Hong Kong.

The talks left key issues like chip exports unaddressed, meaning conflicts are set to emerge in the future, while no one knows how long the current truce will last, he added.

At the midday trading break, China's blue-chip CSI 300 Index .CSI300 was up 0.03%, reversing an earlier loss of as much as 0.6% and climbing back to a three-week high touched in the previous session.

Hong Kong's benchmark Hang Seng index .HSI fell 0.5% to pull back from its highest level in nearly three months.

Tech shares led losses in both onshore and offshore markets. The CSI Semiconductor Index .CSI931865 declined 1.1%, while the Hang Seng Tech Index .HSTECH lost 1% in Hong Kong.

Among major losers, chipmaker SMIC 0981.HK declined 1.7% to a one-week low. Alibaba 9988.HK weakened around 2% and EV-maker Xpeng 9868.HK slid 5%.

The CSI Rare Earth Index .CSI930598 edged up 0.4% after slipping nearly 1% in the morning session, touching the highest level since November.

Chinese markets have been struggling to recover from trade shocks for the past two months, after Trump announced sweeping tariffs on April 2 that threatened the global trade system.

The CSI 300 Index has barely eked out any gains since then, while Hong Kong's benchmark Hang Seng Index has climbed around 4%, with both lagging the around 10% bounce in the MSCI World Index .MIWD00000PUS.

Wang Zhuo, partner at Zhuozhu Investment, said the market is less sensitive to trade talks and investors are shifting their focus to economic fundamentals.

"The key for China now is to bolster manufacturers' confidence, and break the deflationary trend," Wang said.