Tel Aviv - The Israeli government said Tuesday it will only give the final go-head for an announced prisoners swap with Lebanon's Hezbollah militant movement after it receives a final, satisfactory report on missing Israel Air Force navigator Ron Arad.

Israeli Prime Minister Ehud Olmert's representative, Ofer Dekel, signed the prisoners exchange deal in a meeting in Germany Sunday with United Nations-appointed mediator, Gerhad Conrad.

Conrad was also to have handed over to Dekel a thorough report composed by Hezbollah, in which it details the efforts it has made over the years to find out the fate of Arad, whose plane was shot down over Lebanon in 1986 and who disappeared without trace several years later.

But according to Israeli media reports, Dekel refused to bring the report to Israel with him and asked the German mediator to hand it back to Hezbollah, demanding it answer a series of questions that it has left unanswered.

According to the Israeli Ma'ariv daily, Israel among others wants the names and dates of the people whom Hezbollah questioned on Arad.

A senior advisor to Olmert, Mark Regev, would not comment on the details published in the Israeli media, but confirmed Israel had yet to receive the final report.

He said the agreed on timetable for implementation of the deal would only begin after Israel receives the final report.

"The clock will start ticking when we receive the report on Ron Arad," Regev told Deutsche Presse-Agentur dpa.

A statement from the prime minister's office published overnight confirmed that Israel had signed the deal with the UN envoy.

But it warned that "the continued implementation of the deal is conditioned on several components, regarding which no details will be given."

The statement also added that Olmert will again convene his cabinet for final approval of the deal after receiving and studying the report on Arad.

The Israeli cabinet had initially approved the deal in a lengthy and stormy debate Sunday last week.

Israel has nevertheless begun with concrete preparations ahead of the deal.

The Israeli military on Monday began exhuming the bodies of some 190 Hezbollah guerrillas which are to be handed over as part of the swap, which until now was expected to take place sometime next week.

Prior to the exhumations, bulldozers begun clearing vegetation at Israel's "cemetery for fallen enemy soldiers," in the north of the country. The Israeli army on Sunday had declared the burial site, which contains numbered, anonymous graves, a "closed military zone," to enable the preparations.

Hezbollah leader Sheikh Hassan Nasrallah had said last week the exchange would get underway around July 15. Israeli officials too had told local media that the swap would likely happen early or mid-next week.

Under the exchange, Israel is to free Samir Kuntar, its longest- held Lebanese prisoner, as well as four Hezbollah fighters captured in the 2006 Israel-Hezbollah war. It will also hand over the some 190 bodies of Hezbollah guerillas killed in battles with Israel.

Hezbollah, for its part, is to hand over two Israeli reserve soldiers snatched in a July 2006 cross-border raid which had sparked the month-long war. Hezbollah has never allowed the Red Cross to visit its two captives, and released no sign of life from them since they were snatched. Officials in Jerusalem believe the two soldiers, Eldad Regev and Ehud Goldwasser, are dead.

Hezbollah is also to hand over body parts of other Israeli soldiers killed in fighting in Lebanon.

The exchange is to take place via the Red Cross at the northern Israeli border crossing with Lebanon of Rosh Hanikra.

Kuntar is serving multiple life sentences for leading a 1979 infiltration and hostage taking, in which he and his men burst into a residential building in the northern Israeli coastal town of Nahariya, took hostage a father and his four-year-old daughter and killed both. Two Israeli policemen were also killed.

Israel had thus far refused to include Kuntar - seen as a key bargaining chip for information on Ron Arad - in previous prisoner exchanges. (dpa)