SEOUL (Reuters) - South Korean oil and gas companies should invest more in U.S. exploration projects to limit the impact of possible energy policy changes planned by U.S President-elect Donald Trump, the country's vice energy minister said on Thursday.

Trump has called global climate change a hoax and has pledged to walk away from the 2015 Paris Agreement, which was strongly supported by outgoing Democratic U.S. President Barack Obama. Trump has also promised to roll back some of America's environmental policies, which he said would revive the ailing U.S. oil and coal industries.

"Trump administration's energy policy direction contrasts with that of the Obama administration, therefore, substantial changes in domestic and global energy markets are inevitable," Vice Energy Minister Woo Tae-hee said, according to a copy of a speech he was to deliver at an industry forum in Seoul.

"As a result, uncertainty of energy policy is increasing greatly," Woo said.

To minimize the impact of U.S. energy policy changes, Woo urged Korean private companies to look for more opportunities to participate in U.S. exploration projects as U.S. shale gas production is expected to rise.

Woo also suggested that South Korea should expand other cooperation in the oil and gas sector, citing as an example Korea Gas Corp's <036460.KS> long-term shale gas supply deal with U.S. Cheniere Energy <LNG.A>.

The two companies signed a 20-year deal in 2012, and KOGAS is set to start next year to bring 2.8 million tonnes per annum of liquefied natural gas processed by Cheniere to South Korea.

In the renewable energy sector, which is likely to be hit hard by U.S. policy changes, the vice minister said South Korea should bolster cooperation with the U.S. in clean energy fields, including solar power, despite worries over slow market growth.

South Korea unveiled an investment plan worth about $37 billion in early July this year to grow renewable energy and related businesses by 2020 with an aim to cut greenhouse emissions and improve the economy.

(Reporting By Jane Chung; Editing by Tom Hogue)