MEXICO CITY (AP) — The United States' trade representative has expressed concerns on a lack of progress in the renegotiation of the North American Free Trade Agreement at the conclusion of the fifth round of talks in Mexico City.

Robert Lighthizer did not attend this round of talks but said in a statement Tuesday that he saw no evidence Canada or Mexico are willing to accept changes proposed by the U.S. team.

He says that without a rebalancing of the agreement a satisfactory result will not be reached.

A trilateral statement released by the three countries Tuesday says progress was made on a number of chapters in the treaty, but does not provide specifics.

The pact members have scheduled the next round of talks for Jan. 23-28 in Montreal, Canada.