U.S. National Security Agency leaker Edward Snowden?has made an official request for temporary asylum in Russia, lawyer Anatoly Kucherena said Tuesday.

"Because Snowden cannot leave the transit area of the Sheremetyevo (Airport), he completed all necessary forms, wrote a request and gave it to a Russian Federal Migration Service employee invited there for that purpose," the Interfax news agency quoted Kucherena as saying.

The lawyer said earlier in the day he had explained to Snowden the Russian law on refugees, the president's decree on political asylum and the government's resolution on temporary asylum, hinting the whistleblower will make his decision soon.

Kucherena and a number of other lawyers as well as rights campaigners met with Snowden in the transit zone of Sheremetyevo Airport last Friday.

The former U.S. National Security Agency contractor, who has been charged with espionage for revealing the secret U.S. electronic surveillance program Prism, has been caught in legal limbo in the international transit zone of Moscow's Sheremetyevo International Airport since he arrived there from Hong Kong on June 23.