For more than two months, he has been hidden away in an embassy building in west London, shielded from public view and – more pertinently – the hands of the police. Today though, Wikileaks founder Julian Assange emerged into the London sunshine to address his supporters for the first time since his asylum claim.

In a carefully orchestrated appearance from a balcony on the first floor of the embassy building, he demanded that the USA promise not to prosecute Wikileaks staff and to free the alleged source of many of the organisation's leaks. But, in a ten-minute speech, he chose not to address the allegations at the very heart of the whole saga.

“I am here today because I cannot be there with you today,” he told the hundreds of supporters and journalists watching across the street on a sweltering day in west London.

Some thought his first public appearance since fleeing as his impending extradition loomed would present an opportunity to set the record straight or find a resolution to the situation Mr Assange finds himself in. But it was an opportunity Mr Assange chose not to take, instead using it to galvanise support and cast himself as a guardian of free speech, rather than a suspect in an investigation into alleged sexual assault.

He also seized the opportunity make a political point, as he appealed directly to US President Barack Obama to end what he called the “war on whistleblowers”.

Mr Assange said: “as Wikileaks stands under threat, so does the freedom of expression and the health of all our societies. We must use this moment to articulate the choice that is before the government of the United States of America.

“Will it return to and reaffirm the values, the revolutionary values it was founded on, or will it lurch off the precipice dragging us all into a dangerous and oppressive world, in which journalists fall silent under the fear of prosecution and citizens must whisper in the dark?

“I say it must turn back. I ask President Obama to do the right thing. The United States must renounce its witch-hunts against Wikileaks. The United States must dissolve its FBI investigation.”

He told the crowd, which numbered more than 300: “The United States must vow that it will not seek to prosecute our staff or our supporters. The United States must pledge before the world that it will not pursue journalists for shining a light on the secret crimes of the powerful.

“There must be no more foolish talk about prosecuting any media organisation; be it Wikileaks or be it the New York Times.”

And Mr Assange added: “The US administration’s war on whistleblowers must end.” He later demanded that those who have been prosecuted after exposing malpractice be pardoned and that Bradley Manning, allegedly a Wikileaks source who has been locked up without trial in America for nearly three years, be released.

Mr Assange talked at length about his work with Wikileaks. In shorter supply, however, were mentions of the sexual assault allegations Swedish authorities want to question him over.

Some supporters said afterwards that the speech was unlikely to materially affect the outcome of the long-running battle between Mr Assange and the authorities in Britain, Sweden and – many believe – America. Mr Assange himself made no announcements on his intentions or movements in the future.

“This speech is not going to change the situation too much, it is more or less to galvanise the supporters and to show support in turn for everyone out here,” said one 15-year-old Londoner who came to hear Mr Assange speak.

Another, who gave only the name Martin, said: “The fact that he appeared at all was more important than the content of his speech; that is my impression. It was more for the supporters than anything else.”

Naomi Colvin, a supporter of Mr Assange and founder of the Friends of Bradley Manning campaign said she believed Mr Assange should face the allegations which have been made in Sweden but should be able to do so without fear of being extradited to America because of his work with Wikileaks, a move which would require the British government’s explicit consent.

Mr Assange’s lawyer Baltasar Garzon confirmed that his client was seeking a way to guarantee safe passage out of Britain after Ecuador's decision to grant him asylum.

Mr Garzon said: “I have spoken to Julian Assange and I can tell you he is in fighting spirits and he is thankful to the people of Ecuador and especially to the president for granting asylum.

“Julian Assange has always fought for truth and justice and has defended human rights and continues to do so.

"He demands that Wikileaks’ and his own rights be respected. Julian Assange has instructed his lawyers to carry out a legal action in order to protect the rights of Wikileaks, Julian himself and all those currently being investigated."

As Mr Assange gave his speech today from within the boundaries of the embassy – therefore, within the protection afforded by international law - officers from the Metropolitan Police looked on, unable to make the arrest which has been promised. Instead, they tried to hold back supporters and journalists in pens to keep the road open.

Before Mr Assange appeared, some of his supporters gave speeches and members of the crowd used a loudhailer to shout slogans. The historian and writer Tariq Ali addressed them, claiming that Ecuador was backed by the "huge majority" of South Americans in granting Mr Assange asylum.

Mr Ali said: "There is a confrontation which is not of our choosing because the right to claim asylum is the right of any citizen anywhere”. In a statement read out on her behalf, designer Vivienne Westwood said that, through his work, Mr Assange has exposed the “lies” of the authorities. “His fight is our fight,” she added in her letter.

In his statement, film maker Ken Loach wrote: “Julian needs protection from all who care about freedom of information and real journalism.”