German Chancellor Angela Merkel and French President Francois Hollande acknowledged "the necessity" to lower primary surplus targets in  phone talks about a debt deal Wednesday with Prime Minister Alexis Tsipras, Greek sources said.

The three leaders "agreed on the necessity of lower primary surplus (targets) and of an immediate solution" between Athens and its creditors to free up 7.2 billion euros ($8 billion) in frozen bailout aid in exchange for reform and austerity commitments by Greece.

A lower required primary surplus -- a state's budget surplus prior to debt financing -- would allow Athens to respect promises to voters to increase public spending, and has been a main sticking point in negotiations.