A senior Hamas official said on Friday there could be no new exchange talks with Israel until it frees dozens of prisoners it has rearrested since their release in a 2011 swap.

Ismail Haniya, a former Palestinian prime minister, said Israel had re-arrested at least 54 of the more than 1,000 prisoners freed in exchange for soldier Gilad Shalit, who was captured in a cross-border raid by Gaza militants in 2006.

"We have told all the mediators who have mobilised to discuss a new exchange that there won't be any negotiations before the release of all those Israel detained from among the Shalit deal group," he said in a speech marking the Eid al-Fitr holiday.

"There will be no talks without their unconditional release." Haniya did not elaborate on what new exchange was being mooted. Hamas has long acknowledged holding body parts of two Israeli soldiers killed during last summer's conflict in Gaza.

But it has not commented on Israel's announcement last week that Hamas is also holding two of its citizens in Gaza. Hamas and Israeli sources have reported informal, indirect contacts on the possibility of a long-term truce between them, to cement an Egyptian-brokered ceasefire that ended the Gaza conflict last August.

Last Thursday, the Israeli defence ministry said that Avraham Mengistu, an Israeli of Ethiopian descent, had been held by Hamas since crossing illegally into Gaza last September. It said an Israeli Arab is also being held, although it has given no details of his case.

Israel does not allow its citizens to enter Gaza, partly out of fear they may be used as bargaining chips to demand concessions, including the release of prisoners. Israel insists that all of those rearrested since the Shalit exchange were implicated in fresh security offences committed after their release.

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