The implosion of Satyam Computer Services Ltd. may batter the World Bank, which kept quiet until last month about its suspicions the firm engaged in bribery.

As early as 2006, the World Bank told the U.S. Justice Department it suspected Satyam may have been involved in bribery, according to bank officials. In February 2008, it temporarily suspended Satyam from bidding on new contracts, and then in September formally made the firm ineligible to bid on future contracts.

But it didn’t announce the ban, called a debarment, until Dec. 23 — and then only after press reports about it. “The bank should have been more responsible about reporting publicly on what they knew to be misconduct at highest levels of Satyam,” said Bea Edwards, international reform director at the Government Accountability Project, a Washington, D.C., watchdog group.

A World Bank spokesman said it had acted responsibly. “We took the action we needed to take as an institution to maintain our high corporate integrity standards,” the spokesman said.

When World Bank loans are used by governments to hire contractors, the organization publicly discloses any firms that it bans from future work. Instituting the ban can be a long process. Satyam remains eligible to bid for development-project contracts.

But for contracts directly with the World Bank — to supply offices with technology and other services, for instance — it doesn’t routinely disclose firms it blackballs, even if it suspects those firms of bribery. Bank officials say that makes it easier and quicker to cut off firms, but acknowledge privately that it comes at the cost of informing the public.

In the case of Satyam, the World Bank had been looking into the relationship of the computer firm and a senior official at the bank, who it suspected of steering contracts to Satyam in exchange for stock options. In 2006, the World Bank referred the matter to the Justice Department. An official there wouldn’t comment.

In late 2007, the Bank completed an internal investigation and found that Satyam had acted improperly. Under World Bank rules, the company then had the chance to argue why it shouldn’t be banned.