Some estimates put the amount that Japan's government and its central bank spent last week in currency markets to prop up the yen at more than 5 trillion yen, or over 33.6 billion dollars.

On October 21, the Japanese currency temporarily surged by more than 7 yen against the dollar, as the government and the Bank of Japan made an unannounced intervention in the New York foreign exchange market.

According to data released by the BOJ on Monday, nearly 8 billion dollars are expected to be transferred from financial institutions to the government via the central bank on Tuesday.

A financial intermediary company says between 28.2 billion dollars and 28.9 billion dollars were supposed to be wired from the government to financial institutions on the day, if it were not for the intervention.

This works out to the equivalent of over 33.6 billion dollars being wired from financial institutions into the government account on Tuesday. The financial intermediary firm believes most of the funds were spent on last week's intervention.

Market participants speculate that the government and the BOJ were still repeatedly intervening, given the volatility in the foreign exchange market in Tokyo. On September 22, the government and the BOJ intervened in currency markets for the first time in 24 years.