Senior Hamas officials said Monday that the Islamic militant group is still wrangling with Israel over the names of 50 prisoners it wants released in exchange for a captive Israeli soldier, signaling significant gaps in the way of an anticipated deal.

Last week, Israeli and Hamas officials spoke of progress, raising speculation that an agreement could be wrapped up within days. Hamas is demanding some 1,000 prisoners in exchange for an Israeli soldier it has held for more than three years.

But Hamas officials said Israel is still balking at including prominent political leaders and top Hamas militants it holds. The officials spoke on condition of anonymity because of the sensitivity of the German-mediated negotiations.

At the top of the contested list is Marwan Barghouti, a popular leader of Hamas' rival Fatah, who is serving five consecutive life terms for his role in shooting attacks that killed four Israelis and a Greek monk. Barghouti is seen as a possible successor to Palestinian President Mahmoud Abbas, and Israel is wary of freeing him.

Israel is eager to win the release of Sgt. Gilad Schalit, whose plight has generated much sympathy from the public. At the same time, the government fears a deal could bolster Hamas at the expense of Abbas.

A German mediator has been based in Jerusalem for the past three months, shuttling regularly to Gaza to broker terms of the agreement, a Hamas official said. He said that in addition to the 50 disputed names, the sides are also arguing over Israel's demand that some 130 people be deported after their release. Hamas wants that number reduced.

Still, in Gaza, Hamas' interior minister, Fathi Hamad, said Hamas hoped to complete the deal by the Dec. 14 anniversary of its founding, or Dec. 27, the one-year anniversary of a fierce Israeli offensive in Gaza. "It will be a celebration of the liberation of prisoners from the jails of the occupation," he said.

A Palestinian border official confirmed that two German diplomats had entered Gaza from Israel on Monday. The official spoke on condition of anonymity because he was not authorized to discuss the matter with the press. The German Embassy in Tel Aviv declined comment.

Mohammed Nazal, a senior member of Hamas' exiled political leadership based in Damascus, Syria, said progress was being made.

"The German mediator is very active, very professional. He devotes his time shuttling between the Palestinians and the Israelis negotiating over every single name on the list," he said.