0549 GMT - U.S. Treasury yields edge lower in Asian trade, extending Wednesday's falls seen in long-end yields after the Treasury announced an increase of long-end securities buyback volumes. "Whatever the reason, clearly the weakness brought about a response from the U.S. Treasury," Natixis U.S. rates strategist John Briggs says in a note. Natixis reckons that the move was more against the level of yields rather than concerns over the shape of the curve. The fact that the announcement was "very unexpected" sends a strong signal, Briggs says. The 10-year Treasury yield falls 0.8 basis point to 4.644%, while the 30-year yield is down 0.6 basis point at 5.188%, according to Tradeweb.