Washington — The National Institutes of Health would be required to step up its oversight of financial conflicts of interest among university researchers under an amendment adopted today by the Senate Appropriations Committee.

The amendment, which was added to a spending bill for the NIH and the Education Department that the panel passed, 26 to 3, is a response to recent accounts that some researchers have underreported earnings from drug companies. Its adoption comes a day after Sen. Charles E. Grassley, a Republican of Iowa, sent a letter to his colleagues on the Appropriations Committee urging them to “add some teeth” to the regulations that govern conflicts of interest in outside research.

“Researchers need to be put on notice that government grants come with obligations of financial disclosure,” he wrote.

The letter also took aim at the agency itself, calling its oversight “lax.” It cited a report issued in January by the Department of Health and Human Services’ inspector general, who found that the agency had failed to investigate hundreds of conflicts of interest reported by universities. In its response to that report, the NIH said that it was following existing regulations.

The amendment adopted today would require the NIH to update those regulations “for the purposes of strengthening oversight.”

“We need to hold the NIH’s feet to the fire,” said Sen. Tom Harkin, a Democrat of Iowa and member of the panel.

The underlying bill, whose higher-education provisions were otherwise unchanged from Tuesday’s subcommittee vote, would provide a $1-billion increase for the NIH and a $69 increase in the maximum Pell Grant. —Kelly Field