Japan's Mizuho Bank says that technical trouble that has hit its automatic teller machines is expected to have affected more than 1 million transactions worth 700 billion yen ($8.9 billion) by the end of Friday.

Mizuho Financial Group spokeswoman Masako Shiono said that the bank is investigating the problem though has yet to find a cause.

The technical disruptions at Japan's third-largest lender began earlier this week and come after powerful earthquakes centered in northeastern Japan a week ago shook the Tokyo area.

Shiono said the problems were affecting all kinds of settlements including salary payments. Mizuho has 5,600 ATM machines in Japan.