Santos said XRG, an investment arm of the Abu Dhabi National Oil Company, had made an indicative cash offer of $5.76 a share, valuing the Adelaide-based company at $18.7bn. It represents a 28 per cent premium to Santos’s closing share price last week.

But the offer for the ASX’s second-largest oil and gas producer has been met with a lukewarm reception from investors, who say the price could be higher.

Abu Dhabi National Oil Company, preparing an $18.7 billion bid for Santos , is likely to face close scrutiny from Australian regulators worried about local gas supply, but could win them over with pledges to speed up new projects,