Russia’s biggest privately-owned oil producer Lukoil has withdrawn from an oil exploration project in Vietnam, the company’s chief Vagit Alekperov said Wednesday.

Its subsidiary, Lukoil Overseas, bought a 50 percent stake in a project to develop the Hanoi Trough-02 (НТ-02) oil field on the South China Sea shelf in April 2011.

“We have closed the Vietnamese project,” Alekperov said, without further explanation.

The Lukoil chief said the company had other projects, including in Romania, where it would start drilling oil wells in August.

Alekperov also said that Moscow-listed LUKOIL, which already has a secondary listing in London, has suspended plans to list on the Hong Kong Stock Exchange.

“No agreement has been reached, so we’ve put it on hold,” he said.

Lukoil is Russia’s No.2 oil and gas producer by volume.