Mumbai: Extending gains for the third straight session, the BSE benchmark index Sensex on Monday rose by nearly 137 points in early trade on continued buying by funds and retail investors.

The 30-share BSE index, which had gained 56.67 points in the past two sessions, rallied further by 136.79 points, or 0.79 percent, to 17,324.13 with all sectoral indices, led by realty and IT, trading in the positive zone clocking gains of up to 1.43 percent.

The wide-based National Stock Exchange index Nifty moved up by 32.70 points, or 0.63 percent, to 5,241.70.

Brokers said increased buying by funds as well as retail investors at prevailing levels, mainly helped Sensex to rise further.

In the Asian region, the Hong Kong's Hang Seng Index rose by 1.18 percent in early trade on Monday. Japanese markets are closed on Monday. The US Dow Jones Industrial Average ended 0.18 percent higher in previous session on Friday.