US security whistleblower Edward Snowden has scooped an annual prize awarded by former CIA staff for showing "integrity in intelligence," the ex-agents said.

Mr Snowden fled to Russia to escape espionage charges after disclosing the vast scope of US surveillance operations.

The Government Accountability Project gave Mr Snowden the Sam Adams Award - a "symbolic candlestick" - at a ceremony in Moscow late on Wednesday.

Those present included former National Security Agency senior analyst Thomas Drake, former Department of Justice ethics adviser Jesselyn Radack, former FBI agent Coleen Rowley and former CIA analyst Ray McGovern.

The group - which says its mission is to promote corporate and government accountability - said the award is "given annually by a group of retired CIA officers for members of the intelligence community who exhibit integrity in intelligence."

The ex-spooks did not disclose any details about where in Moscow Wednesday's ceremony took place, but Ms Radack said: "Edward looks great. He's centred, articulate, and closely following the issues, both in the United States and globally.

"He loves America and wants to see it returned to its democratic ideals, which are completely antithetical to a closed and secret society that make for turn-key tyranny," she added.

Word of the prize surfaced the same day that Mr Snowden's father landed in Russia to meet his son for the first time since the former US spy agency contractor became a fugitive.