Stanford University has charged taxpayers $2,500 to refurbish a grand piano, $3,000 for a cedar-lined closet and $2,000 a month for flower arrangements at the residence of the university's president, according to congressional investigators.

The charges were discovered after questions were raised in federal audits about millions of dollars that Stanford has billed the government for research in recent years.

Last week, faced with questions from the investigators, Stanford disclosed it had repaid $184,286 it said it had erroneously charged the government for depreciation on a 72-foot yacht and on other equipment.

The Office of Naval Research, which monitors Stanford's payments for all government research, said yesterday that a five-person team will be sent to Palo Alto, Calif., to investigate the allegations concerning the billing practices.

"We have recently discovered a number of charges that have been absorbed by the government that neither I nor the taxpayers financing these costs would consider reasonable or proper," Rep. John D. Dingell (D-Mich.) said in a letter asking auditors to step up their probe.

Dingell indicated similar problems may exist at other universities, and investigators said that Stanford is the first of several schools that will come under scrutiny.