RIO DE JANEIRO, Brazil -- National Security Agency leaker Edward Snowden wrote in a lengthy "open letter to the people of Brazil" that he's been inspired by the global debate ignited by his release of thousands of NSA documents and that the agency's culture of indiscriminate global espionage "is collapsing."

In the letter, Snowden commended the Brazilian government for its strong stand against U.S. spying.

He wrote that he'd be willing to help the South American nation investigate NSA spying on its soil, but could not fully participate in doing so without being granted political asylum, because the U.S. "government will continue to interfere with my ability to speak."

Revelations about the NSA's spy programs were first published in the Guardian and The Washington Post newspapers in June, based on some of the thousands of documents Snowden handed over to Barton Gellman at the Post and to Brazil-based American journalist Glenn Greenwald and his reporting partner, Laura Poitras, a U.S. filmmaker.

The documents revealed Brazil is the top NSA target in Latin America, with spying that has included the monitoring of Brazilian President Dilma Rousseff's cellphone and hacking into the internal network of state-run oil company Petrobras.

The revelations enraged Rousseff, who in October cancelled an official visit to Washington that was to include a state dinner. She's also pushing the United Nations to give citizens more protections against spying.

In his letter, Snowden dismissed U.S. explanations to the Brazilian government and others that the bulk of metadata gathered on billions of emails and calls was more "data collection" than surveillance.

"There is a huge difference between legal programs, legitimate spying ... and these programs of dragnet mass surveillance that put entire populations under an all-seeing eye and save copies forever," he wrote. "These programs were never about terrorism: they're about economic spying, social control, and diplomatic manipulation. They're about power."

Brazilian senators have asked for Snowden's help during hearings about the NSA's targeting of Brazil, an important transit hub for trans-Atlantic fiber optic cables that are hacked. Both Greenwald and his domestic partner, David Miranda, spoke before the Senate, and Miranda has taken up the cause of persuading the Brazilian government to grant political asylum to Snowden.

"Brazil is a big, strong country, I think one of the few nations in the world that could offer asylum to Edward Snowden," Miranda said in a phone interview. "He's helped so many nations, and I think mine like all others that have sworn to defend human rights should step forward to help him now."

Miranda said he received Snowden's letter directly from the former NSA analyst via "secure means." Snowden lives in Russia on a temporary one-year visa.

"He just wants to continue the work that he began six months ago" when he first handed over documents to Greenwald and Poitras, Miranda told The Associated Press in an interview.

Snowden "can't participate in the debate that's happening now because Russia doesn't allow him to take part," Miranda said. "But if he were to be given permanent asylum, particularly here in Brazil ... I think he can help the entire world and Brazil understand the situation."

Snowden previously requested political asylum in Brazil and several other nations.

In July, Brazil's Foreign Ministry choose not to respond to Snowden's request, technically not denying it and therefore leaving it pending and open to approval.

On Tuesday, neither Brazil's Foreign Ministry nor the presidential office said they had immediate comment on Snowden's letter or his asylum request.

Several members of Brazil's Congress have called for Snowden to receive asylum so he could assist lawmakers' investigation into NSA activity in Brazil.

Sen. Vanessa Grazziotin, who heads the Senate panel investigating U.S. espionage in Brazil, said Snowden's letter shows that "he wants to co-operate, but without imposing any conditions."

"His help would be more than helpful, but it all must be done in such a way so as not to jeopardize our relationship with the United States," she said in a phone interview. "I personally defend the idea that Brazil should grant Snowden political asylum for humanitarian reasons only, not in exchange for information."

U.S. officials have remained steadfast in their stance on Snowden, accusing him of leaking classified information and saying he should face felony charges in American courts.

Rousseff recently joined Germany in pushing for the United Nations to adopt a symbolic resolution that seeks to extend personal privacy rights to all people.

She has also ordered Brazil's government to take several measures, including laying fiber optic lines directly to Europe and South American nations, to "divorce" Brazil from the U.S.-centric backbone of the Internet that experts say has facilitated NSA spying.

The Snowden letter was first published Tuesday in a Portuguese translation by the newspaper Folha de S. Paulo. The AP obtained the original English version, which was then later widely made available online.

It comes one day after a U.S. district judge ruled the NSA's bulk collection of millions of Americans' telephone records likely violates the U.S. Constitution's ban on unreasonable search. The case is likely to go to the Supreme Court for a final decision.