* U.S. comments suggest new support for Taiwan

* AstraZeneca begins enrolling 30,000 in COVID-19 vaccine study

* Dollar hits two-year trough as Fed commits to easy policy

* Despite stock pullback, S&P posts best August since 1986

By Alwyn Scott

NEW YORK, Aug 31 (Reuters) - Asian stocks were set to weaken on Tuesday following a softer Wall Street close while the dollar slipped as markets digested new Federal Reserve comments that suggested rates will stay low for an extended period.

Australia's S&P/ASX 200 lost 0.89% in early trading, while Japan's Nikkei 225 fell 0.22%,

Hong Kong's Hang Seng index futures lost 0.38%.

Wall Street declines overnight were caused by month-end portfolio rebalancing "rather than a new trend in equities," said Rodrigo Catril, senior FX strategist at NAB Market Research in Sydney.

The Dow Jones Industrial Average and the S&P 500 ended in the red, while the Nasdaq rose solidly. The S&P gained more than 7% for the month to notch its best August since 1986 in what is traditionally a softer month for stock performance.

"After such a strong summer run we're reverting back to the old pandemic playbook, so we see tech outperforming," said Mona Mahajan, senior U.S. investment strategist at Allianz Global Investors in New York. "Really, that's a defensive move as people think about stay-at-home more as we're heading toward that fall season."

Investors in Asia await the release of China manufacturing data and an interest rate decision from the Australian central bank. While the Reserve Bank of Australia is not expected to change policy, its commentary on the economic outlook will be closely watched.

Most stocks slid overnight, but chalked up another month of gains for August. U.S. tech shares rose again Monday, powered by stock splits that lifted Apple Inc and Tesla Inc .

Providing some support to sentiment was AstraZeneca's plan to enroll 30,000 participants in a late-stage study to evaluate its COVID-19 vaccine candidate, AZD1222. Vaccine news often lifts markets.

Taiwan stocks could see a boost after the U.S. said on Monday it was establishing a new bilateral economic dialogue with the country, an initiative it said was designed to support Taipei.

Fed Vice Chair Richard Clarida on Monday expanded on Governor Jerome Powell's comments from last week, saying that under the U.S. central bank's new policy view, a low rate of unemployment does not on its own trigger higher interest rates.

Last week, the Fed said its new strategy plan is to use higher inflation when the economy is robust to offset the impact of periods of weaker prices.