DHAKA (Bloomberg) - At least 20 foreign citizens were involved in the cyber theft of US$81 million (S$110 million) from Bangladesh's central bank, according to a senior investigator in the case.

The names and nationalities of the suspects would be disclosed later, Shah Alam, additional deputy inspector general of Bangladesh's Criminal Investigation Department, told reporters in Dhaka on Monday (April 18).

"The names of the foreign nationals came up during our official visits to the Philippines and Sri Lanka this month as part of our investigation," Alam said. "We may have to visit those countries again, but we can't disclose the names at this moment for the sake of the investigation."

Hackers attempted to steal almost US$1 billion from Bangladesh's account at the Federal Reserve Bank of New York in early February. While the Fed blocked most of the transfers, about US$81 million ended up in the Philippines, and most of that is missing. Another US$20 million sent to a bank in Sri Lanka was returned.

The case has sparked investigations in the Philippines and Bangladesh, and prompted central banks around the globe to double check cyber security systems.

Bangladeshi investigators also found evidence of neglect among several central bank officials, Alam said.

"We have to find out if the officials at Bangladesh Bank had any criminal intention or they just got involved in the episode unknowingly," he said.