German Finance Minister Wolfgang Schaeuble on Sunday rejected pressure to beef up the euro zone's permanent rescue facility, saying Berlin would stick to the agreement made in December for a lending capacity of 500 billion euros ($646 billion).

We are sticking to what was agreed in December, Schaeuble told public broadcaster ARD. In March we will check whether that is sufficient.

The draft treaty establishing the European Stability Mechanism (ESM) will be discussed by euro zone finance ministers on Monday and is likely to be approved by EU leaders at their summit on January 30, euro zone officials have said.

Leaders from the single-currency bloc will review in March whether the limit of 500 billion euros is sufficient.

Markets and the European Commission, the European Central Bank, the United States, Canada and Japan, have been calling for the euro zone to bolster the capacity of its bailout funds.

But the euro zone's main paymaster, Germany, remains opposed. Schaeuble said Germany was doing more than its fair share to resolve the euro zone's debt crisis, and it was apparent that markets were beginning to regain confidence.

We are not yet out of the woods but over the last few weeks, many (debt) auctions have shown that the markets are beginning to regain confidence.

Schaeuble said debt-stricken Greece was having difficulty implementing reforms but would have to; otherwise, the situation cannot be resolved.

(Reporting by Sarah Marsh; Editing by Dale Hudson)