Bangladesh's central bank confirmed on Sunday that cyber criminals tried to withdraw $951mn from its US bank account, as the country's finance minister said he first got to know of one of the biggest bank heists in history through the media.

Unknown hackers breached the computer systems of Bangladesh Bank, and transferred $81mn from its account at the Federal Reserve Bank of New York to casinos in the Philippines between February 4 and February 5.

Finance Minister Abul Maal Abdul Muhith said the central bank did not inform him about the heist, and that he learned of it only a month later when news first appeared in the media.

"I am very much unhappy about the handling of the issue," he told reporters in his office in Dhaka.

He said he planned to meet Prime Minister Sheikh Hasina on Sunday and decide what action to take against central bank officials.

The cyber heist and its global scale has left Bangladesh officials scrambling to find answers and recover the money that was lost.

The incident has also left other banks and businesses around the world eager to learn more, so they can review their own networks for signs that they are vulnerable to similar attacks or might already have been breached.

Bangladesh Bank said in a Facebook post that hackers made 35 separate requests to withdraw money from its Fed account, totalling $951mn, confirming earlier reports.

Officials said the account, used for international settlements, had billions of dollars.

Bangladesh officials expect that it would be difficult to recover the money that has already gone out of the banking channels.

Officials have said that the money that made its way to the Philippines was further diverted to casinos and then possibly on to Hong Kong.

After a meeting with the investigators and central bank officials on Sunday, Mohammad Aslam Alam, the secretary of the banking division of the ministry of finance, said recovery could take months.

But he added that the Philippines had managed to freeze $68,000, which Dhaka should be able to recover.

The Bangladesh Nationalist Party (BNP), the largest opposition party, demanded the resignation of the central bank governor and the finance minister.