SINGAPORE (Reuters) - Singapore shares rose slightly on Wednesday, heading for a second consecutive session of gains, with commodity firms Noble Group and Olam International among the biggest gainers.

The benchmark Straits Times Index was up 0.2 per cent, while MSCI's broadest index of Asia-Pacific shares outside Japan was 0.7 per cent higher.

The prices of soft commodities have been rising over the past couple of months due to dry weather in key producing parts of the world such as Brazil, California and Southeast Asia, Barclays said in a report.

Political unrest in Ukraine and Russia also threatens supplies from that part of the world, Barclays said.

"We believe Wilmar, Olam, Noble and Golden Agri (in that order) benefit most from the extraneous threats to the supply of soft commodities that have been emerging in the past two months."

Olam shares soared 6.4 per cent to a nine-month high of $1.915, with 12.7 million shares changing hands as of midday, more than 2.5 times its average 30-day daily trading volume.

Noble shares rose 3.8 per cent to a two-month high of $1.08, with trading volume more than 1.5 times the 30-day daily average, extending gains from Tuesday after sources told Reuters that China's biggest grains trader COFCO Corp is in talks to buy its agribusiness arm.