A day-long outage at Japan's interbank clearing network left 1.4 million money transfers made by customers of the country's 11 largest banks in limbo.

The downtime hit at 8.30am on Tuesday morning, with normal service unlikely to resume until Wednesday at the earliest.

The glitch at the Zengin interbank data communication system left more than a million customers unable to transfer money to accounts at other banks.

The systems operator, Zengin.Net said that a back up system was put into production to deal with the bulk of the backlog, with the remaining funds transferred on Wednesday.

The Zengin platform at its peak processes 6.5 million transactions worth $81 billion every day. It is the first such outage to affect the system in the 50 years since its inception in 1973.