* SSEC -0.8%, CSI300 -1.4%, HSI -1.0%
* HK->Shanghai Connect daily quota used 3.1%, Shanghai->HK daily quota used -0.6%
* FTSE China A50 -1.2%
SHANGHAI, April 12 (Reuters) - China and Hong Kong stocks started the week on a downbeat note on Monday, as worries over policy tightening persisted on expectations of upbeat economic data due later this month.
** The CSI300 index fell 1.4% to 4,964.39 at the end of the morning session, while the Shanghai Composite Index lost 0.8% to 3,422.70.
** Leading the declines, the CSI300 materials index and the CSI300 transport index slumped 3.4% and 3.9%, respectively.
** China's Q1 economic growth data probably would beat market expectations, which could raise worries over a quick tightening of monetary policy, Huaan Securities noted in a report.
** The market could also encounter challenges as much stronger than expected PPI could lead to marginal changes in monetary policy, the brokerage added.
** Denting sentiment were ongoing Sino-U.S. tensions.
** U.S. Secretary of State Antony Blinken said on Sunday the United States is concerned about China's aggressive actions against Taiwan and warned it would be a "serious mistake" for anyone to try to change the status quo in the Western Pacific by force.
** In Hong Kong, the Hang Seng index dropped 1.0% to 28,417.24, while the Hong Kong China Enterprises Index lost 1.0% to 10,865.51.
** China's Alibaba does not expect any material impact from changes to its exclusivity arrangements with merchants, CEO Daniel Zhang said on Monday, after regulators fined the e-commerce giant a record $2.75 billion for abusing its market dominance.
** Shares in Alibaba Group Holdings Ltd rose as much as 9% in Hong Kong trade.
** "In the short term, Ali will have a rebound because (the fine) cleared the air," said Louis Tse, managing director of Wealthy Securities in Hong Kong.
** "Of course they don't want to kill the goose that can lay the golden eggs," he added.
** However, the Hang Seng tech index slid 1.6%, on worries that other platform companies could face antitrust fines. (Reporting by Luoyan Liu and Andrew Galbraith; editing by Uttaresh.V)
