The West Australian government will allow onshore gas producers to export a portion of their output to international markets to boost investment in the sector and prevent future domestic shortfalls, but has stopped short of imposing tougher measures on offshore producers.

Premier Roger Cook on Thursday confirmed onshore producers would be afforded a six-year window to sell 20 per cent of their gas to more lucrative LNG export markets, but some commentators fear it will fail to move the dial in terms of encouraging exploration and development.