SINGAPORE - A surprise move by the Bank of Japan (BOJ) to boost monetary stimulus sent Asian stocks surging on Friday.

The local benchmark Straits Times Index gained 39.94 points, or 1.2 per cent, to end at 3,274.25.

There were 319 gainers, versus 93 losers.

Tokyo shares soared 4.8 per cent to their highest level since November 2007.

Hong Kong advanced 1.3 per cent, Shanghai rose 1.2 per cent, Sydney climbed 0.9 per cent and Seoul added 0.3 per cent.

"You're getting a double boost with talk of the Japanese Government Pension Investment Fund increasing its shares allocation and the BOJ pumping more cash in at a faster rate," said Mr Shane Oliver, a Sydney-based head of investment strategy at AMP Capital Investors, in an interview with Bloomberg.

"It had become increasingly apparent that what the BOJ was doing wasn't enough and they needed to do more, and it's always been a question of when they would do that. It's an excellent outcome."