CAMBRIDGE Mass. (Reuters) - An animal-rights group has called on the U.S. Department of Agriculture to fine the Massachusetts Institute of Technology because of a January incident in which a rabbit at a research lab died when it was left in its cage while it was sent for cleaning.

The group, Stop Animal Exploitation Now, which opposes the use of animals in medical research, on its website called on people to contact USDA officials and seek a $10,000 fine.

MIT said in a letter to the National Institutes of Health, which oversees the use of animals in scientific research, that the incident occurred in January, when an employee of the school was cleaning a cage that housed three rabbits.

The employee removed two of the rabbits from the cage but failed to take out the third before putting the cage into a sanitizing machine. The employee, an 11-year-veteran of the school who was not identified, resigned later that month.

"MIT deeply regrets that the accidental death of a rabbit occurred," a university spokeswoman said in a statement. "MIT took immediate steps to put in place new protocols to prevent this from happening again."

The university now requires two people to check cages to confirm they are empty before sterilizing them.

USDA officials did not immediately respond to a request for comment.

The agency fined Harvard Medical School $24,000 in December after finding repeated animal welfare violations that resulted in the deaths of four monkeys since 2011.

(Reporting by Scott Malone; Editing by Bill Trott)