(Reuters) - The European Central Bank abruptly canceled its acceptance of Greek bonds in return for funding on Wednesday, shifting the burden onto Athens' central bank to finance its lenders and isolating Greece unless it strikes a new reform deal.

The move, which means the Greek central bank will have to provide its banks with tens of billions of euros of additional emergency liquidity in the coming weeks, was a response to what many in Frankfurt see as the Greek government's abandoning of its aid-for-reform program.

The decision came just hours after Greece's new finance minister Yanis Varoufakis emerged from a meeting with ECB President Mario Draghi to claim that the ECB would do "whatever it takes" to support member states such as Greece.

Tsipras did much of the negotiating for the deal rather than Greece's Eurogroup representative, Varoufakis. But sources close to the government said this reflected Tsipras's need to win backing from Syriza's left wing and his right-wing coalition partner, the Independent Greeks party.

Their support will be crucial in maintaining government unity during negotiations for the long-term agreement.

Likewise Tsipras needs to keep public support. Costas Panagopoulos, who heads the Alco polling firm, said the initial reaction was relief that Greece would stay in the euro. Greeks might even accept Tsipras's change in language and assertions that the troika is no more. "It may sound odd but this could turn into political gains," he told Reuters.