Reuters:
The magazine said the extra 15 billion euros were needed because of the deteriorating economic situation in Greece, echoing a Reuters report on Thursday.
Der Spiegel quoted a representative of the troika of foreign leaders -- the European Commission, IMF and the European Central Bank -- saying: "We're assuming that it won't be possible to collect missing money solely from the private creditors."
Talks with private creditors on swapping existing Greek bonds for longer-term debt made significant progress on legal and technical issues and will continue Saturday, both sides said late on Friday.
A preliminary deal could be sealed by Sunday evening, a Greek government official said, with the aim of submitting a public offer to bondholders by Feb. 15.