ConocoPhillips, the US oil group, plans to invest up to A$9.6bn (US$7.8bn) jointly to develop coal-seam methane gas assets with Origin Energy, the Australian energy group fighting a hostile A$13.8bn takeover offer from BG Group of the UK.

The deal underlines the level of international interest in Australia’s vast energy reserves, particularly cleaner fuels such as liquefied natural gas. ConocoPhillips and Origin plan to convert the gas extracted from coal-bed methane into LNG before it is exported from the Australian state of Queensland to Asia.