French President Nicolas Sarkozy said debt-ridden Greece's entry to the eurozone was a mistake.
Greece was "not ready" when it joined in 2001, he said, adding that it could be rescued thanks to a new deal on the debt crisis.
European leaders worked into the early hours of Thursday in Brussels to secure an agreement aimed at preventing the crisis from spreading to larger eurozone economies.
The deal triggered a worldwide shares rally.
The head of the eurozone's bailout fund is beginning attempts to persuade China to invest in a scheme to help rescue member countries facing debt crises.
After meeting Chinese leaders, Klaus Regling said there were no formal negotiations and would be no deal now.
It is thought China may pay about 70bn euros ($100bn) into the fund, which is expected to be boosted to 1tn euros.
