The Japanese central bank made an early injection of two trillion yen, followed by another one trillion later in the day.

The BoJ has made emergency injections twice daily for the past four days, and the latest brings the total to 11 trillion yen since Tuesday.

The world's central banks have pumped hundreds of billions of dollars into money markets to ensure the supply of funds does not dry up since the collapse of US investment bank Lehman Brothers.

The world's top central banks also announced a huge operation to boost the volume of dollars available. The US Federal Reserve agreed to inject US$180 billion as part of a global total of US$300 billion dollars.

The Tokyo Stock Exchange's benchmark Nikkei-225 index was up more than three per cent in the morning session after the concerted action.

Bank of Japan governor Mr Masaaki Shirakawa said on Thursday he hoped the central banks' actions would help bring stability to international markets. -- AFP