His legal case worker, John Tipple, said the charges cited an interview in The Guardian in which he claimed troops on the ground had been confused about the purpose of their presence as far back as 2006, and that fellow soldiers had supported his cause after he called for a complete withdrawal of troops.

The new charges carry a maximum of 10 years' imprisonment in addition to the three to four years he could face if the desertion charge is upheld.

It has emerged that British public servants at the Defence Ministry are being paid more than £8000 ($14,300) a month to work in Afghanistan, nearly five times as much as some soldiers on the front line.

Ministers said the payouts were justified in part by the fact that some officials were posted to conflict zones.

The ministry said the maximum monthly additional payment for a senior grade official working in a conflict zone was £8250. For more junior officials, it was £6750. The allowances are paid on top of basic salaries.