TOKYO, Aug 27 (Reuters) - Japanese shares closed lower on Thursday, with consumer discretionary and telecommunications stocks leading the declines, as investors were worried about U.S.-China relations and awaited a speech by U.S. Federal Reserve chairman.

The Nikkei 225 Index ended down 0.35% at 23,208.86, while the broader Topix index fell 0.53% to 1,615.89.

The United States blacklisted 24 Chinese firms and targeted individuals it said were part of construction and military actions in the South China Sea, while a U.S. defence official said China had launched four ballistic missiles into the sea.

Meanwhile, Fed Chairman Jerome Powell will address the Fed's annual central bankers' conference later in the day, usually held in Jackson Hole, but being conducted virtually this year because of the COVID-19 pandemic.

He is expected to outline changes to the Fed's monetary policy framework that will allow it to keep rates lower for longer.

"The chance of a flare-up between China and the United States is low, but these developments are just enough to put some downward pressure on Asian equities," said Kiyoshi Ishigane, chief fund manager at Mitsubishi UFJ Kokusai Asset Management.

Also weighing on sentiment was a likely a press conference by Japanese Prime Minister Shinzo Abe on Friday to address concerns about his health.

The top underperformers on the Topix 30 were East Japan Railway Co down 2.56%, followed by insurer Tokio Marine Holdings Inc which shed 2.24%.

The stocks that gained the most among the top 30 core Topix names were job placement company Recruit Holdings Co Ltd up 5.62%, followed by Shin-Etsu Chemical Co Ltd that rose 0.23%.

There were 45 advancers on the Nikkei index against 178 decliners.

The volume of shares traded on the Tokyo Stock Exchange's main board was 0.79 billion, compared with an average 1.16 billion in the past 30 days. (Reporting by Stanley White; Editing by Subhranshu Sahu and Uttaresh.V)