WASHINGTON — Senator Rand Paul suffered five broken ribs and bruises to his lungs in an altercation with a neighbor on Friday at his home in Bowling Green, Ky., one of the senator’s advisers said on Sunday. The injuries, which the adviser said left Mr. Paul in considerable pain, appear to be much worse than the “minor” injuries that the police had reported on Saturday.

Doug Stafford, a senior strategist to Mr. Paul, said in a statement that it was unclear when the senator would be able to return to work.

According to a criminal complaint, Mr. Paul told the police that he was tackled from behind after the neighbor entered his property, NBC News has reported. The senator also had cuts to his nose and mouth and had trouble breathing because of the rib injuries, the complaint said. Mr. Stafford attributed the injuries to “high-velocity severe force.”