Greek Prime Minister Alexis Tsipras said Athens was ready for a "difficult compromise" which may eventually involve new concessions, a government source said Saturday.

"If we arrive at a viable accord, even if it is a difficult compromise, we will take up the challenge because our only criteria is to get out of the crisis," Tsipras was quoted as telling Greek officials Friday in a government statement.

Athens dispatched a team of his top advisers to Brussels on Saturday to attempt to thrash out a deal to avert a default.