Sept. 16 (Bloomberg) -- Woodside Petroleum Ltd., Australia’s second biggest oil and gas producer, rose to the highest in 11 months in Sydney trading on speculation of a discovery at a Sierra Leone venture where it holds a stake.

Woodside gained 4.8 percent, the most since Aug. 20, to A$50.82 on the Australian stock exchange, the highest close since Oct. 2. The benchmark ASX 200 Index rose 2.4 percent.

Anadarko Petroleum Corp., the second-largest producer of natural gas in the U.S., may disclose as early as today the establishment of a new oil field off the west coast of Africa, the Financial Times reported, citing people familiar with the situation. The Venus-B well discovery forms part of a 1,000- kilometer (620-mile) oil frontier stretching from Ghana to Sierra Leone, the FT said.

“If we had something material to mention we would have done so,” Roger Martin, Perth-based spokesman for Woodside, said by phone today. The company owns a 25 percent stake in blocks SL6 and SL7, Martin said.

Tullow Oil Plc, the U.K. explorer with the most licenses in Africa, owns a 10 percent stake in the Sierra Leone permit area, while Spanish oil company Repsol YPF SA has 25 percent, the FT said.

To contact the reporter on this story: Ben Sharples in Melbourne at bsharples@bloomberg.net

Last Updated: September 16, 2009 02:59 EDT