ISLAMABAD Interior Ministry and the US Embassy are at the loggerheads over use of non-registered vehicles with different number plates by the Embassy. Well-placed sources told TheNation on Sunday that a serious row has erupted between the Interior Ministry and the US Embassy after the Lahore incident on Saturday in which Lahore Police had impounded a non-registered vehicle which the US Embassy claimed was its property. Lahore Police, the sources said impounded two vehicles and one of them was returned to the US Embassy after proof of its ownership. However, the non-registered vehicle has not been released. The Interior Ministry, a source said, has turned down the US Embassy plea seeking release of the impounded car. The Ministry has taken serious note of the incident that has shaken confidence of the local law enforcement agencies, the source said.