SHANGHAI/SINGAPORE (Reuters) -Chinese stocks tumbled on Wednesday alongside their Hong Kong peers, as investors booked profits after a blistering rally and as officials failed to inspire confidence in stimulus plans intended to revive the economy.

Benchmark indexes in China declined more than 5% by midday in a sharp reversal from the moves seen the day before, when markets returned from the week-long National Day holiday with a bang and scaled more than two-year highs.

The Shanghai Composite index fell 5.3%, while the blue-chip CSI300 index dropped 5.4%, both poised to snap a 10-day winning streak.

The A-share market, comprising stocks listed in Shanghai, Shenzhen and Beijing, had a roller-coaster ride on Tuesday, with turnover hitting a record 3.485 trillion yuan ($493.17 billion).

But gains were capped after officials fell short of delivering further details of Beijing's massive stimulus measures at the highly anticipated National Development and Reform Commission (NDRC) press conference on Tuesday, leaving investors disappointed.

"I would say the NDRC's recent announcements were a bit disappointing, mainly because there wasn't much in the way of new stimulus or clear forward guidance," said Nori Chiou, investment director at White Oak Capital.

However, he said Wednesday's pullback in stocks was hardly a letdown for many, given their strong run over the previous sessions.

Hong Kong's Hang Seng index similarly dropped 1.4%, though it remains one of the region's best-performing markets this year following its steepest rally in a generation over recent weeks.

The Hang Seng Mainland Properties Index slid 4.7%, while technology shares shed 0.86%.

"The market is widely anticipating a fiscal stimulus announcement sometime this month, something like 2-3 trillion yuan is the range being talked about," said Alvin Tan, head of Asia FX strategy at RBC Capital Markets.

"The positive sentiment on China assets lately is premised on expectation of a major fiscal stimulus package, so that sentiment will turn quickly if we don't get some package at least matching the range above."

Tourism shares were among the top losers on Wednesday, as data showed that spending during the Golden Week holiday was yet to recover to pre-COVID levels. An index tracking the performance of the sector lost 7.9%.

Shares of property companies were also among the biggest losers. The CSI300 Real Estate index plunged 9.7%, reflecting lingering concerns over the strength of the recovery in China's beleaguered property market.

Elsewhere, Singapore-traded FTSE China A50 futures fell nearly 3%.

($1 = 7.0665 Chinese yuan)