The US military is weighing up whether to force Halliburton to pay back what could amount to tens of millions of dollars in fees it charged the army to pay for private security subcontractors in Iraq.

Tina Ballard, deputy assistant secretary of the army, said it was investigating allegations that Halliburton violated the terms of its $16bn (£8bn, €12bn) logistics contract in Iraq, known as Logcap, by knowingly or unknowingly paying for private security subcontractors, and that the army would consider taking steps to recoup those funds.