By Alun John

HONG KONG, April 21 (Reuters) - Mainland China and Hong Kong stocks fell on Thursday, hurt by worries about the Chinese economy, but an overnight tumble in longer dated U.S. treasury yields lent support to other benchmark indexes.

A 0.78% drop for Hong Kong and 0.36% decline for blue chips in mainland China pulled MSCI's broadest index of Asia-Pacific shares outside Japan 0.22% lower.

But share benchmarks in Australia and Korea were up, while Japan's Nikkei rose 0.81%. Nasdaq futures gained 0.6% and S&P500 futures advanced 0.4%.

The 10-year yield was last at 2.8455%, a whisker higher in Asia morning trade, but still bruised after falling overnight from as high as 2.981% in early trade on Wednesday.

"I think we're still heading towards 3% for 10 year treasuries, I think it was a little bit of profit taking," said Rob Carnell, head of research for Asia Pacific at ING.

Carnell said the fall in bond yields may have provided some support for equities overnight, with the S&P500 broadly flat on the day despite an uglier picture for tech.

He added that "equity futures look positive, with Asian markets also showing some signs of positive risk appetite for the near term."

The tech-heavy Nasdaq fell 1.22%, dragged down by Netflix which plunged 35.1% after reporting a surprise decline in subscribers. The blue chip Dow rose 0.71%.

China was a focus for investors again, after surprising markets on Wednesday by keeping benchmark lending rates unchanged, despite frequent government pledges to support a slowing economy hit by its worst COVID-19 outbreak in two years.

China's central bank, however, set the midpoint rate for the yuan at its the weakest since November on Wednesday, ahead of the lending rate announcement. It also set it lower still on Thursday.

"The CNY fixing reflected an admission that things aren't going brilliantly in China, and they need a bit more support, but they've been holding off from doing that with interest rates. They don't want to drive the yuan much weaker than they want it to be, but they've decided to take back some recent strength," said Carnell.

Lower yields sent the dollar lower, with the dollar index tumbling 0.65% on Wednesday as the beaten down euro and sterling managed to recover a little ground.

The dollar index was last at 100.44, down from a near two-year peak the previous day of 101.03.

The dollar gained 0.38% on the yen to 128.3 in early trading on Thursday, however, as the yen's recovery on Wednesday - its first session of gains against the dollar in nearly two weeks - proved short-lived.