Greece and its creditors went back to the drawing board on all terms of a planned debt swap as they fight to overcome an impasse in talks and stave off a painful default.

Talks broke down last week over the interest rate Greece will offer on new bonds and a plan to enforce investor losses. Both sticking points will be discussed in the negotiations in Athens on Wednesday.

"All variables are being considered," said a Greek government official, who requested anonymity, calling the interest rate on the new bonds Greece will offer in the swap the most "visible" aspect of the talks.

Al Jazeera's Andrew Simmons reports from Athens.