CITIGROUP Inc, the biggest United States bank, will ban off-site meetings among its own employees and cut back on color photocopying as part of a plan to clamp down on expenses as investment banking revenue declines.

Executives in the New York-based bank's institutional clients group will need to ensure spending is "highly efficient," according to an internal memorandum.

A Citigroup spokesman in London confirmed its contents to Bloomberg News yesterday.

Employee meetings must be held within Citigroup offices and client events will require approval, the memo said. Color photocopiers will be removed from some locations and their use will be limited to client presentations. The memo didn't say how much money the new rules will save the bank.

"We will be conducting a review of our BlackBerry usage," Citigroup said. "In the interim, all new BlackBerries will require pre-approval."

Citigroup cut about 14,000 jobs in the first half after reporting US$55 billion of write-downs and credit losses in the past year, more than any other bank, according to data compiled by Bloomberg.

"We have spent considerable time looking at our headcount and related expense, and while we have made progress in that area, we still have more work to do," the memo said.

Financial firms globally have eliminated 101,250 jobs since the beginning of the credit crunch. Other banks are also tightening their belts. Deutsche Bank AG requires deal makers to get their managers' approval for taxi journeys in advance, and business meals must not exceed US$92 per person, the Independent newspaper reported.

Citigroup is also scaling back external training, which will be limited to that which is "strictly necessary," the memo said.

Purchases of computer hardware and software must also be pre-approved under the new rules, as must all non-client travel, the bank said.