ExxonMobil , long regarded by its peers and investors as the most successful interational oil company, is beginning to show signs of weakness, revealing on Thursday that it is struggling to increase oil production and to squeeze profit out of its refining business.

The world’s biggest energy group announced a first-quarter record profit of $10.9bn but its oil production fell almost 10 per cent in the first three months of the year and refining profits slumped.