WIKILEAKS, whose spectacular publication of classified data shook the world and exposed the inner workings of international diplomacy, might be weeks away from collapse, the organisation's leader said.

Though its leaks spread outrage and embarrassment across military and diplomatic circles, WikiLeaks' inability to overturn the block on donations imposed by American financial companies might prove its undoing.

"If WikiLeaks does not find a way to remove this blockade, we will simply not be able to continue by the turn of the new year," founder Julian Assange told London's Frontline Club.

As an emergency measure, Assange said, his group would cease what he called "publication operations" to focus its energy on fundraising. He added that WikiLeaks, which he said had about 20 employees, needed an additional R28-million to keep it going into 2013.

WikiLeaks, launched as an online repository for confidential information, shot to notoriety with the April 2010 disclosure of footage of two Reuters journalists killed by a US military strike in Baghdad, Iraq.

The Pentagon had claimed that the journalists were likely "intermixed among the insurgents", but the helicopter footage, which captured US airmen firing on prone figures and joking about "dead bastards", unsettled many across the world.

In the following months WikiLeaks published nearly half a million secret military documents from the wars in Iraq and Afghanistan. As a whole, the documents provided an unprecedented level of detail into the grueling, bloody conflicts. Individually, many raised concerns about the actions of the US and its local allies - for example by detailing evidence of abuse, torture and worse by Iraqi security forces.

Though US officials railed against the disclosures, claiming they were putting lives at risk, it wasn't until WikiLeaks began publishing a massive trove of 250000 US State Department cables in 2010 that the financial screws began to tighten.

One after the other MasterCard Inc, Visa Europe Ltd, Bank of America Corp, Western Union Co and Ebay Inc's PayPal stopped processing donations to WikiLeaks, starving the organisation of cash as it was coming under intense political, financial and legal pressure.

Assange said the restrictions, imposed last December, had cut off about 95% of the money WikiLeaks could have received.

Each company gave its own explanation for the blockade, expressing some level of concern over the nature of the secret-spilling site.

But WikiLeaks supporters say MasterCard and Visa still process payments for the Ku Klux Klan or the far-right British National Party and that WikiLeaks or its staff have not been charged with any crime.