Two satellite phones stolen in Iraq cost the Foreign Office almost £600,000 in bills, a spending watchdog says.
It is not known exactly when the phones were stolen
It took about 18 months before the phones were cut off, despite a junior staff member in the Foreign Office telephony unit querying the huge bills.
The National Audit Office said neither senior staff nor the Iraq Policy Unit bothered to look into it and continued to pay the itemised monthly bills.
The Foreign Office confirmed that the phones had been lost.
A spokesman said the department had held an internal investigation into the incident.
"Disciplinary action is being taken against some members of staff for allowing the loss to take place," he said.
One bill included calls to a South Pacific number totalling £289,991 - made to a £5.95 a minute number in the Wallis and Futuna Islands.
Action was finally taken after the service provider also queried the level of calls.
The phones were among 10 sent to Iraq in 2003, but an internal Foreign Office inquiry failed to establish exactly when or where they were stolen from.
It concluded that they had probably never been issued officially and "it was likely that they had been stolen early in 2004 from the stock of phones held in Baghdad or Basra".
One phone stopped working in March 2005 and the other three months later.
The bill also included calls on a third phone which was rented in 2004 and switched off one month after it was stolen.