Abu Dhabi National Oil Company’s potential acquisition of Gunvor, the energy trading house, has reached an impasse due to disagreements over the deal’s size, people familiar with the negotiations said.

While Adnoc had hoped to acquire all of Gunvor, or a majority stake, the commodity trader’s chief executive Torbjörn Törnqvist is unwilling to yield control of the group he co-founded in 2000, people involved in the discussions said.

Törnqvist, who controls almost 90 per cent of Gunvor, has told Adnoc he is willing to sell only a minority stake to raise funds to drive growth.

Gunvor and Adnoc declined comment.