Asian shares turned cautious on Friday after a Nvidia-fuelled technology rally, while currency and bond markets awaited U.S. Federal Reserve chair Kevin Warsh's remarks on interest rates, according to RTHK.

In Hong Kong, the Hang Seng Index opened down 155 points, or 0.61 percent, at 25,410. The tech index slipped 39 points, or 0.85 percent, to 4,580, while the China Enterprises Index fell 64 points, or 0.76 percent, to 8,425. In mainland China, the Shanghai Composite Index opened down six points, or 0.16 percent, at 3,950. The Shenzhen Component Index lost 29 points, or 0.21 percent, to 14,019, and the ChiNext Index edged down 19 points, or 0.57 percent, to 3,453.

In Tokyo, the Nikkei was down 27 points, or 0.04 percent, at 66,104 at the open before rising as much as 507 points, or 0.77 percent, to 66,639 before noon. In Seoul, the Kospi was down 65 points, or 0.95 percent, at the open and was 73 points lower at one stage before lunch.

Markets are focused on the Fed's Jackson Hole Symposium, where Warsh is slated to speak today. Three Fed officials have already warned about sticky inflation, while the central bank chief has resisted giving forward guidance on the path of interest rates. Futures imply about a 35 percent chance of a rate increase at the Fed's September 16 meeting and are fully priced for a move by December. ANZ analysts said markets hope Warsh will reduce uncertainty around the Fed's reaction function, but warned that too little guidance could trigger an adverse market reaction. Longer-dated yields have risen since the Fed's July meeting as Warsh was seen as not offering enough concrete steps to address persistently high inflation.