Venezuela's president, Nicolas Maduro, has offered asylum to former US intelligence contractor Edward Snowden in defiance of Washington, which is demanding his arrest for divulging details of secret US spy programmes.

Snowden, 30, is believed to be holed up in the transit area of Moscow's Sheremetyevo international airport and has been trying to find a country that would take him since he landed there from Hong Kong on June 23.

"In the name of America's dignity - I have decided to offer humanitarian asylum to Edward Snowden," Maduro said, speaking at a military parade marking Venezuela's independence day. "He is a young man who has told the truth, in the spirit of rebellion, about the US spying on the whole world."

Russia has kept the former National Security Agency contractor at arm's length, saying the transit area where passengers stay between flights is neutral territory and he will be on Russian soil only if he goes through passport control.

It was not immediately clear how Snowden would react to Maduro's offer, nor how he would reach Venezuela if he accepted it. There are no direct commercial flights between Moscow and Caracas. And, given the dramatic grounding in Vienna of the Bolivian president's plane last week over suspicions that Snowden was on board, using European airspace could prove problematic.

Russia has shown signs of growing impatience over Snowden's stay in Moscow. The country's deputy foreign minister said on Thursday that Snowden had not sought asylum in Russia and needed to choose a place to go. Moscow has made clear that the longer he stays there, the greater the risk of the diplomatic standoff over his fate causing lasting damage to Russia's relations with Washington.

Both Russia's foreign ministry and president Vladimir Putin's spokesman declined to comment on Venezuela's offer.

But senior pro-Kremlin lawmaker Alexei Pushkov, head of the international affairs committee of Russia's lower house of parliament, said asylum in Venezuela would be Snowden's best option.

The White House declined to comment on the matter.

Raising the possibility of at least one other option, Nicaragua said it had received an asylum request from Snowden and could agree to it "if circumstances permit".

WikiLeaks, the anti-secrecy organisation, said on Twitter on Friday that Snowden had asked six more nations for asylum, bringing to about 20 the number of countries he has appealed to for protection from US espionage charges.

WikiLeaks said it would not reveal which six new countries Snowden had applied to for asylum, due to "attempted US interference".

However, Maduro said Venezuela was ready to offer him sanctuary. He added that the details Snowden had revealed of US spy programmes had exposed the nefarious schemes of the US "empire".

"Who is the guilty one? A young man - who denounces war plans, or the US government which launches bombs and arms the terrorist Syrian opposition against the people and legitimate president Bashar al-Assad?" he asked, to applause and cheers from ranks of military officers at the parade.

Since narrowly winning a presidential election in April that followed the death of his mentor, Hugo Chavez, from cancer, Maduro has often lambasted the US, even accusing the Pentagon and former US officials of plotting to kill him.

■US/VEnezuela