US Attorney General Eric Holder has reassured his Russian counterpart that whistleblower Edward Snowden will not be tortured or given the death penalty if Moscow extradites him.

The information emerged after the US Department of Justice disclosed the contents of a July 23 letter, which had generated fevered speculation on both sides of the Atlantic. 

Holder’s letter – in which he also promises that the former NSA contractor would receive a full civilian trial – directly addresses Snowden’s previously expressed fears.

"I believe that, given these circumstances, it is unlikely that I would receive a fair trial or proper treatment prior to that trial, and face the possibility of life in prison or even death," Snowden wrote in the cover letter for the multiple asylum applications he submitted around the world over the past few weeks.

Edward Snowden currently remains in Moscow’s Sheremetyevo airport, as his temporary asylum application is reviewed.

Snowden faces charges of theft of government property, unauthorized communication of national defense information and willful communication of classified communications intelligence information to an unauthorized person. The maximum tariff for the latter, more grave crimes, is 10 years in prison.

Additional charges may be added following an investigation, but Holder has promised Russian justice minister Aleksandr Konovalov that even if those carry a potential death penalty, the ultimate sanction will not be applied.

Moscow and Washington do not have an extradition agreement, though Moscow has handed over US citizens on a case-by-case basis in the past.

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