The sex scandal involving call girls and President Obama’s bodyguards will cost US taxpayers $1.5 million, it was revealed.

A team of U.S. investigators flew to Cartagena, Colombia, to launch a sweeping probe that has already cost tens of thousands of dollars.

The team is investigating allegations that a dozen U.S. Secret Service agents and 11 military security men cavorted with as many as 20 prostitutes while they were preparing for the President to attend a trade summit last weekend.

One of the two Colombian women at the centre of the furore, which has so far cost six bodyguards their jobs, broke down in tears when she gave her account of the weekend.