(Adds fund manager quote, more details)
SHANGHAI, April 24 (Reuters) - China stocks tumbled more than 1 percent on Monday in their worst day this year amid signs that Beijing will tolerate further market volatility as regulators increasingly clamp down on shadow banking and speculative trading.
Market confidence also has been hit by an expected flood of initial public offerings which will pump more supply into the weakening market, and by worries that the world's second-largest economy will start to lose steam in coming months.
Recent signs of stability in China's economy "have provided a good external environment and a window of opportunity to reduce leverage in the financial system, strengthen supervision and ward off risks," the official Xinhua News Agency reported on Sunday.
"Over the past week, interbank rates trended higher, bond and capital markets suffered from sustained corrections and some institutions faced liquidity pressure. But these have little impact to the stability of the broader environment."
The Xinhua comments quashed lingering hopes that the government will step in to stem a further stock market slide, as it did during a crash in mid-2015.
"You cannot count on the National Team for rescue this time," said Shen Weizheng, fund manager at Ivy Capital, referring to a group of government-backed investors.
Chinese stocks have been on a downward trajectory since mid-April and have lost nearly 3 percent this month, wiping out a good chunk of their gains so far this year.
The Shanghai Composite Index slumped 1.4 percent to 3,129.53 points -- its worst one-day loss in four months -- after suffering its biggest weekly decline of 2017 last week.
The blue-chip CSI300 index fell 1.0 percent to 3,431.26.
Daily declines of more than 1 percent in the indexes have been rare for notoriously volatile Chinese markets this year, though some highly speculative small cap shares have seen wild swings as first speculators, then regulators piled in.
"Even the better-than-expected Q1 data could not boost the market, as investors are concerned about regulatory risks," wrote Larry Hu, an analyst at Macquarie Capital Ltd, referring to stronger-than-expected 6.9 percent economic growth early in the year.
He added that "the last thing policy makers want to see amid the Party Congress this fall is a market crash like that in summer 2015. And the outstanding economic performance in Q1 gives them more room to tighten."
In the latest of a flurry of regulatory measures in recent weeks, China's insurance regulator said on Sunday it will ramp up its supervision of insurance companies to make sure they comply with tighter risk controls.
It also threatened to investigate executives who flout rules aimed at rooting out risk-taking.
The banking regulator said late on Friday that growth in Chinese wealth management products (WMPs) and interbank liabilities eased in the first quarter, suggesting authorities are making some headway in containing financial risks built up by years of debt-fuelled stimulus.
But while the clampdown is expected to continue, most analysts believe the moves will be cautious to avoid hitting economic growth, and some sceptics believe authorities will continue to put off deeper and more painful reforms.
Investors are already concerned that the economy could lose momentum in coming months as local governments launch ever more stringent measures in a battle to cool heated property prices.
"Market risk appetite could continue to decline if financial regulation keeps tightening," said Gao Ting, Head of China Strategy at UBS Securities.
"Investors seem to mostly be responding by adjusting their positions, particularly by rotating into high-quality blue-chips."
Another big concern for investors has been the pace of new IPOs.
Up to 500 IPOs are expected to be approved to raise no more than 300 billion yuan ($43.57 billion) in 2017, an official with Shanghai Stock Exchange was quoted as saying.
Dozens of newly-listed stocks had lost more than 30 percent over the past weeks amid tougher regulation and expectations of more equity supply.
On Monday, 2,620 stocks fell, while only 390 plays rose.
Main sectors fell across the board, led by infrastructure stocks, which dived more than 3 percent.
Bearish sentiment spread to major investment themes, including Beijing's ambitious "One Belt, One Road" infrastructure plan to eventually connect China to European markets, and the high-profile new Xiongan Economic Zone near Beijing.
The Shanghai Stock Exchange said it would pay special attention to excessive speculation in stocks related to the Xiongan concept, and would take more stringent regulatory measures if needed to contain abnormal speculative activities that disturb the market.
$1 = 6.8861 Chinese yuan renminbi Reporting by Samuel Shen, Luoyan Liu and John Ruwitch; Editing by Kim Coghill