Singapore's Keppel Corp, the world's largest offshore oil rig builder, posted a 10 percent rise in third-quarter profit on Thursday, but said expansion in rig fleets could be constrained by tight credit.

Keppel said that given the likelihood of further deterioration in global economies, it was focusing on consolidating and executing its existing orderbook, which remained unchanged from the previous quarter.

"A slowdown in rig orders over the next 12-15 months should not have too significant an impact on us."

Oil prices have more than halved since early July, leading analysts to say the sector might see order cancellations, as fears of weaker fuel demand could reduce a push for oil exploration.

"We believe that the fundamentals underpinning rig and FPSO demand are still intact although in the foreseeable future, some rig owners' ability to expand their fleet could be constrained by tight credit," Keppel added.