Julian Assange wearing a Guy Fawkes mask during a debate in London (Twitter)

Sweden has summoned Ecuador's ambassador to Stockholm and called the decision to grant WikiLeaks founder Julian Assange political asylum "unacceptable".

The 41-year-old, who has been staying in the Ecuador embassy in central London since 19 June to avoid extradition to Sweden, where he is wanted for questioning over allegations of sexually assaulting two women, praised the "courageous" act of Ecuador after he was finally granted asylum.

"It is a significant victory for myself, and my people. Things will probably get more stressful now," he told embassy staff.

He thanked Ecuador's President Rafael Correa and his government. "It was not Britain or my home country, Australia, that stood up to protect me from persecution, but a courageous, independent Latin American nation," he said.

"While today is a historic victory, our struggles have just begun. The unprecedented US investigation against WikiLeaks must be stopped."

Ecuador's foreign minister, Ricardo Patino, had asked Sweden to guarantee that he would not be extradited on to the US to face charges relating to the leak of thousands of diplomatic cables, which caused headaches for governments all around the world two years ago.

The Swedish government refused to give a guarantee.

Assange had promised to hand himself over to Swedish prosecutors if the US guaranteed it would drop a grand jury investigation into allegations against him and any further inquiry of WikiLeaks's publishing activity.

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