NSA whistleblower lands in Russia after Hong Kong allows him to leave, with WikiLeaks saying it is providing assistance

Edward Snowden, the NSA whistleblower, has arrived in Moscow after Hong Kong authorities allowed him to leave despite a US request for his arrest.

In a statement, WikiLeaks said the 30-year-old was heading to a democratic country "via a safe route" for asylum purposes and that the organisation was assisting at his request. Snowden had been in hiding in Hong Kong since identifying himself as the source of revelations on US surveillance programmes.

His flight from US authorities, which want to charge him with espionage, appeared set to continue with an onward flight west from Moscow to Havana on Monday. From there, various reports indicated that he would try to get to either Caracas or Quito.

The Hong Kong government said on Sunday he had left of his own accord "through a lawful and normal channel" and said the request filed by the US did not fully comply with legal requirements. Pointedly, it also said it wanted Washington to clarify Snowden's claims that the US had hacked targets in the territory.

The move came two days after the US announced it had charged him with espionage and hours after the US stepped up pressure on Hong Kong to issue a provisional warrant for Snowden's arrest with a view to his surrender.

Snowden had previously said he would stay in Hong Kong and fight for his freedom through the courts. He had been at a safe house since 10 June, when he checked out of his hotel after giving an interview to the Guardian revealing himself as the source who leaked top secret US documents.

His unexpected departure comes a day after the US sought to turn up pressure on the territory, with a senior administration official telling the Washington Post: "If Hong Kong doesn't act soon, it will complicate our bilateral relations and raise questions about Hong Kong's commitment to the rule of law."

Sunday's statement from the Hong Kong authorities said: "Since the documents provided by the US government did not fully comply with the legal requirements under Hong Kong law, the HKSAR government has requested the US government to provide additional information so that the department of justice could consider whether the US government's request can meet the relevant legal conditions.

"As the HKSAR government has yet to have sufficient information to process the request for provisional warrant of arrest, there is no legal basis to restrict Mr Snowden from leaving Hong Kong.

"The HKSAR government has already informed the US government of Mr Snowden's departure.

"Meanwhile, the HKSAR government has formally written to the US government requesting clarification on earlier reports about the hacking of computer systems in Hong Kong by US government agencies."

Vans belonging to the Russian presidential administration wait by the Aeroflot plane believed to be carrying Edward Snowden at Moscow airport. Photograph: Mirian Elder

A spokesperson declined to reply to further queries.

Snowden is believed to have boarded Aeroflot SU213 on Sunday morning, bound for Moscow's Sheremetyevo airport. Reuters cited an airline source who said the whistleblower would fly on to Cuba on Monday, before travelling on to Venezuela.

Snowden had earlier cited Iceland as a possible refuge in an interview with the Guardian.

In a statement, WikiLeaks said: "He is bound for a democratic nation via a safe route for the purposes of asylum, and is being escorted by diplomats and legal advisers from WikiLeaks.

"Mr Snowden requested that WikiLeaks use its legal expertise and experience to secure his safety. Once Mr Snowden arrives at his final destination his request will be formally processed."

Dmitry Peskov, spokesman for the Russian president, Vladimir Putin, said: "I don't [know if he's planning to stay in Moscow]. I heard about the potential [arrival] from the press. I know nothing."

On whether Moscow would still consider a request for asylum from Snowden, Peskov added: "Every application is considered so it's standard procedure … We are not tracing his movements and I know nothing."

Simon Young, director of the Centre for Comparative and Public Law at the University of Hong Kong, described the news of Snowden's departure as "a shocker".

He said: "The US government will be irate with their Hong Kong counterparts [and] may even question whether the Hong Kong government was acting in good faith pursuant to their treaty obligations. I have no doubt that they were, and it is quite common for government lawyers to seek more information on surrender or mutual legal assistance requests before local process can begin."

But Young noted that given the very low threshold for a provisional warrant – simply providing evidence that the person was in Hong Kong and that he or she was wanted for prosecution in the US – Washington "will wonder why the Hong Kong government feels the surrender paperwork needs to be fully in place before the provisional warrant can be obtained".

The US department of justice was not immediately available for comment and the ministry of foreign affairs in Beijing has yet to comment.

Lawyers had said a legal battle over Snowden's surrender from Hong Kong could have lasted years, but had also warned that in the long run he was unlikely to prove successful.