The U.S. Treasury Department said on Thursday that China's yuan remains undervalued, but it declined to say that China or any other country manipulates their currencies for trade advantage.

In a long-delayed semiannual report on trade practices of key U.S. partners, Treasury said China's move last month to end a peg between the yuan -- also known as the renminbi -- and the dollar was significant.

What matters is how far and how fast the renminbi appreciates, Treasury added, as it pledged to closely monitor the results.

(Reporting by Glenn Somerville and David Lawder; Editing by Leslie Adler)