Singapore shares inched up in their fifth day of modest gains, led by commodities firm Noble Group, whose share price jumped to the highest level in nearly five months.

The benchmark Straits Times Index edged up 0.4 per cent to 3,208.36 points, while the MSCI's broadest index of Asia-Pacific shares outside Japan eased as investors await United States labour market data later in the day.

Noble Group shares rose as much as 3.9 per cent to $1.07, matching a peak in late May. The stock has risen nearly 10 per cent in the last four sessions.

Citi analysts kept their target price on Noble Group at $1.26, expecting an improvement in the company's long-term margins as its assets and investments start to contribute.

A fire last week at Brazil's Port of Santos, the world's main source of raw sugar shipments, could benefit Noble Group's sugar business as Copersucar, the world's largest sugar trader, looks for alternatives from suppliers including Noble, to help meet its obligations, Citi analysts say.

"These events at Santos aside, FY13 remains challenging earnings-wise as it (Noble) continues work on maturing its Brazilian sugar investments as well as its oilseeds crushing expansion in Ukraine, South Africa and Brazil," Citi said in a research note.

Palm oil company Wilmar International rose nearly 3 per cent to a five-month high of $3.44, followed by agricultural products firm Olam International, which rose 2.7 per cent.

The worst performer on the index, Hutchison Port Holdings Trust, dropped 1.3 per cent to US$0.755, recovering slightly from a near six-week low of US$0.74 hit earlier in the day, after it reported an 8.4 per cent drop in net profit for the quarter ended Sept. 30.

OCBC downgraded the stock to "hold" from "buy", as it lowered its forecast for 2013 throughput for HPHT's ports in Hong Kong and Shenzhen, and trimmed its target price to US$0.74 from US$0.84.