* SSEC up 1.88%, CSI300 climbs 2.47%
* Trading volume surges as uncertainty eases
* Huawei suppliers lead gains as Trump offers olive branch
* Rare earth firms slump
* Trade relief may be temporary-analysts
SHANGHAI, July 1 (Reuters) - Chinese shares jumped in heavy trade on Monday after the United States and China agreed to restart trade negotiations and Washington said it would postpone further tariffs, offering investors hope of a resolution to the increasingly damaging trade war.
While there were no signs of progress on key sticking points in the trade dispute, the promise of more talks and concessions offered by U.S. President Donald Trump, including an easing of restrictions on tech company Huawei, lifted the blue-chip CSI300 index 2.47% higher.
The benchmark Shanghai Composite index gained 1.88% to 3,034.80 points, despite fresh signs of domestic economic weakness in factory activity surveys.
The smaller Shenzhen index was up 2.93% by midday and the start-up board ChiNext Composite index jumped 3.2%. Hong Kong markets were closed for a holiday.
Volumes surged as investor uncertainty over trade eased. About 15.59 billion shares have traded so far on the Shanghai exchange, roughly 74.9% of the market's 30-day moving average of 20.82 billion shares a day, and compared with 18.14 billion shares for the full trading day on Friday.
"The external risks that have been troubling markets for a long time have been temporarily resolved, and A-shares welcome restored risk appetite," Yang Liu, an analyst at Minsheng Securities, said in a note.
After meeting with Chinese President Xi Jinping in Osaka on Saturday, Trump said China had agreed to make unspecified new purchases of U.S. farm products and return to the negotiating table.
But while Trump said the talks are "back on track", existing tariffs remain in place and the meeting produced no deadline for progress on a deal.
Information technology firms led the gains, with suppliers to Huawei Technologies Co surging after Trump said the U.S. Commerce Department would study in the next few days whether to take Huawei off the list of firms banned from buying components and technology from U.S. companies without government approval.
A sub-index tracking IT firms jumped 4.90% and one tracking telecoms companies added 3.89%.
Rare earth producers slumped after rallying in recent weeks as trade war tensions intensified.
Xi had visited a rare earth firm in southern China in May, fuelling speculation that China could cut off supplies of the metals, a key ingredient in high-technology consumer electronics and military equipment, to the United States as part of the trade war.
JL MAG Rare-Earth Co Ltd, which hosted Xi in May, fell 3.91%.
Broader market gains came despite further signs of weakness in China's manufacturing sector, with both private and official activity surveys pointing to contraction last month.
On Monday, the Caixin/Markit Manufacturing Purchasing Managers' Index (PMI) for June came in at 49.4, its worst level since January and below expectations.
That followed a worse-than-expected reading in the country's official manufacturing survey, released on Sunday.
"The latest survey data suggest that Chinas economy is coming under renewed pressure as a result of cooling foreign demand and waning fiscal support, which should trigger further monetary easing," Capital Economics said in a note.
China's yuan also gained on the trade ceasefire, with spot yuan quoted at 6.839 per U.S. dollar, 0.38% firmer than the previous close of 6.865.
(Reporting by Andrew Galbraith; Editing by Kim Coghill)