WASHINGTON (Reuters) - U.S. military personnel rammed into the gate of a medical aid group's hospital in Afghanistan last week to enter the grounds of the building hit in a U.S. air strike earlier this month, a Pentagon spokesman said on Monday.

Medecins Sans Frontieres, or Doctors Without Borders, said in a statement on Friday that a U.S. tank had entered the grounds of its hospital in Kunduz without permission, damaging the compound, destroying potential evidence, and distressing its staff.

Department of Defense spokesman Captain Jeff Davis said on Monday that the vehicle in question was not a U.S. tank, but rather an Afghan tracked vehicle transporting a U.S. team on Oct. 15 to conduct an inspection to determine the structural integrity of the building.

The team mistakenly believed there were no MSF personnel at the site, and rammed into the gate to gain access to the compound, Davis said.

"Unbeknownst to our team there were MSF personnel and they were understandably not happy," Davis said. "They should have coordinated ahead of time and they are going to make it right and make sure that that gate is repaired."

An Oct. 3 air strike on the MSF hospital killed at least 22 staff and patients. The U.S. military has taken responsibility for the air strike, which occurred during intense fighting between Afghan forces and the Taliban.

The Islamist militants had briefly taken control of Kunduz city, in their biggest military victory in 14 years of war.

MSF officials have said the hospital's location had been clearly indicated to all parties, and that no Taliban fighters were occupying the site, as some Afghan government officials initially stated.

(Reporting by Yeganeh Torbati; Editing by Tom Brown)