Britain and Ecuador face a prolonged showdown over the fate of WikiLeaks founder Julian Assange, who is holed up in the South American nation's London embassy, Britain's foreign minister says.

Assange took shelter in the Ecuadorian embassy in London in June after exhausting all appeals against extradition from Britain to Sweden, where he is wanted for questioning over sexual assault allegations.

Ecuador has granted him diplomatic asylum.

Britain's Foreign Secretary William Hague told reporters in New York talks with Ecuador's Vice President Lenin Moreno in August over the Australian activist had yielded little progress and negotiations would continue.


"I've seen no sign of any breakthrough since our meeting," Hague said.

"The position was to uphold the law in the United Kingdom. That remains the position. This may go on for some time."

Assange is set to appear by videolink at a meeting on the sidelines of the UN General Assembly in New York this week.

The British minister is to hold talks with Ecuador's Foreign Minister Ricardo Patino in New York on Thursday.

Patino will then speak with the WikiLeaks founder.

Assange, 41, fears Sweden will hand him over to the United States, where he could face prosecution over WikiLeaks' release of a vast cache of leaked Iraq and Afghanistan war reports and diplomatic cables.

The activist's lawyers and supporters say he would not get a fair trial in the United States.

Ecuador has reportedly made one proposal that Assange be transferred to Sweden but stay under the protection of the Ecuador government.