Thursday's decision, though expected after a brief setback in talks this week, saw Greek stocks <.ATG> extend earlier losses and fall 0.9 percent, with the banking stock index <.FTATBNK> down 3.1 percent. The two-year Greek government bond yield rose.

Later Thursday, Greece's parliament had scheduled a vote designed to tie up those loose ends in creditor talks, clearing a last hurdle with creditors and allowing the payment of a tranche of bailout money.

While Greece is still rated 'junk' by credit agencies, the ECB cannot waive a its own requirement that government paper it accepts is investment grade, unless creditors deem the country fully compliant with its rescue programme.

"Possibly at the next meeting of the ECB we could see a lifting of the waiver," Greek Prime Minister Alexis Tsipras told his cabinet in comments broadcast live on state TV.

That is not expected for about three weeks.

ECB NOT READY

At a news conference in Vienna, ECB President Mario Draghi said the bank had discussed the issue of reinstating the so-called 'waiver', but said the bank was not ready to act yet.

"We had a presentation, we had no decision. The Governing Council acknowledges the significant progress made in the last few months," Draghi said.

"Once the prior actions (under the bailout agreement) are implemented, the Governing Council will take a decision leading to the reinstatement of the waiver," Draghi said.

Greece and its lenders wrapped up the bulk of reforms needed to get bailout cash last week, but left some loose ends which must be tied up before Athens gets 10.3 billion euros (7.95 billion pounds ) of sub-tranches by September.

Later Thursday, parliament was expected to adopt further pension reforms and set a timetable for the sale of a stake in the country's power grid operator.

Greek banks lost access to the ECB's main refinancing operations in early 2015 when Athens refused to meet its bailout commitments, exacerbating its debt crisis and almost pushing the country out of the euro zone.

Since then, the lenders have relied on the ECB's Emergency Liquidity Assistance, where the average interest rate charged is estimated to be around 100 to 150 basis points above the ECB's benchmark interest rate.

“A small delay is not an issue," said George Poulopoulos, Chief Financial Officer (CFO) at Piraeus Bank, Greece’s largest lender.

"Once the Euro Working Group gives its clear signal on the prior actions it is expected that the waiver will be reinstated at the ECB’s next governing council meeting."

(Additional reporting by Balazs Koranyi in Frankfurt, Lefteris Papadimas in Athens; Editing by Jeremy Gaunt and Toby Chopra)

By Francesco Canepa and George Georgiopoulos

Stocks treated in this article : Piraeus Bank SA, National Bank of Greece, Attica Bank SA