29/03/2011 (Reuters) - Singapore shares fell 0.8 percent by midday on Monday, weighed by weaker palm oil prices, although shipbuilder COSCO Corp surged after the company secured a major rig contract provided some support for the market.

Wilmar International , the world's largest listed palm oil firm, fell 1.7 percent to S$5.27, hurt by lower palm oil futures on expectations of higher output and lacklustre demand in March.

Smaller rival Golden Agri Resources also retreated 1.5 percent to S$0.68 with over 27.6 million shares traded.

By the midday break, the Straits Times Index (STI) was down 23.45 points at 3,047.39. The total value of shares traded in the morning session was S$704.2 million, down from S$845.3 million on Friday.

"The lethargic performance today may be attributable to uncertainties within the market, particularly from the Middle East and Europe regions," said Ng Kian Teck, an analyst at SIAS Research.

With the index having gained almost 5 percent last week, dealers said some retail investors decided to take profits due to lack of positive catalysts.

Ng said he expects the STI to continue trading in negative territory in the afternoon with support at 3,028.

"Markets has more or less settle down on the ongoing Japanese nuclear issue. With the market having risen a little, I think some investors are taking some money off the table," said a local trader.

Shares Chinese shipbuilder COSCO surged as much as 4.5 percent and hit a one-month high after it signed an agreement to build two rigs worth $1.05 billion, prompting CIMB to upgrade its rating to neutral from trading sell. [ID:nL3E7ES04F]

At the midday, shares of COSCO were 2 percent higher at S$2.05 with nearly 23 million shares changing hands.

Shipbuilder STX OSV rose as much as 2.6 percent on Monday to a one-month high after it said it had secured a contract to build a platform supply vessel, traders said.