"As we have stated previously, any political or economic consequences of our decision regarding the asylum request are outweighed by our legal and humanitarian obligations," an embassy statement said.
Last year, Ecuador granted asylum to WikiLeaks founder Julian Assange, who remains in the nation's embassy in Britain.
Ecuador's rationale appeared to have won support from former U.S. President Jimmy Carter. If another country wants to give haven to Snowden, "then that is their right as a sovereign nation," he told CNN's Suzanne Malveaux. "If the United States can acquire custody of him, I'm sure he will be brought to trial, and that's the way the law should be implemented."
Snowden's acts may have some positive impact, Carter said.
"He's obviously violated the laws of America, for which he's responsible, but I think the invasion of human rights and American privacy has gone too far," he said.
"I think that the secrecy that has been surrounding this invasion of privacy has been excessive, so I think that the bringing of it to the public notice has probably been, in the long term, beneficial."
Asked to elaborate, he said, "I think the American people deserve to know what their Congress is doing."
Snowden has been at Moscow's international airport since Sunday, when he arrived from Hong Kong.