AOG also outlined to the market a number of reasons why shareholders should reject the Ensign offer. Firstly, the company said Ensign's offer did not include a premium for the company's position as a leading Australasian and international oilfield contractor.

Secondly, the offer did not take into account forecast earnings growth to be derived from recent rig acquisitions and long-term contracts as well as strong demand in the oil and gas market.

Thirdly, AOG said shareholders could give up the opportunity of more attractive offers as other international drilling companies have expressed interest in the group.

AOG also told the market it rejects Ensign's assertions that its share price has been underperforming and said AOG shares have outperformed the All Ordinaries Index and the Small Industries Index. In addition, AOG has paid a dividend of between 8 cents and 10 cents per share in four of the last five years, the company said.

AOG shares are currently trading at $1.87, up 6c on yesterday.