There is growing concern in Israel that the recent tightening of sanctions against the Gaza Strip will result in international pressure to transfer control of the border crossings into the Strip to the Palestinian Authority.

PA Prime Minister Salam Fayyad had proposed during last month's donor nations conference in Paris that Palestinian forces not affiliated with the rival Hamas and Fatah factions take over operations at the crossing points. Fayyad is also considering the possibility of involving private international companies specializing in border crossings, who would assist PA officials in running them.

In recent weeks Fayyad has been hard at work trying to convince the U.S. administration, the United Nations and the European Union of the merit of his idea.

Political sources in Jerusalem said Monday that the idea is enjoying growing international support. Senior U.S. officials have sent a number of memos to Israeli counterparts describing Fayyad's idea as "creative and worth a serious look."

Israeli sources quoted American officials saying that "Fayyad is a person we completely trust and if he is proposing such an idea it is worthwhile to assist him and approach the matter favorably."

Fayyad's proposal also enjoys the support of many European states, including Britain, Spain, France and the Netherlands.

Reflecting on the effect on international public opinion of the recent blockade in response to the Qassam attacks, visiting Dutch Foreign Minister Maxime Verhagen said Monday that "the pressure on the civilian population will not help solve the Qassam rockets, but will only result in greater support for Hamas.

"Israel must find a way to cooperate with Abu Mazen [PA President Mahmoud Abbas] and Fayyad to reopen the crossings," Verhagen said.

At this stage Israel has reservations about Fayyad's proposal, but has not rejected it. One of the arguments against the proposal is that Hamas will utilize the transfer of control to increase its strength and break out of the international isolation imposed on the group.

"Opening the crossings by Fayyad, without coordination with Hamas, is impossible," a senior diplomatic source in Jerusalem said Monday.

"Opening the crossings with the agreement of Hamas means the group is granted legitimacy. This can only result in a weakening of Fayyad and a bolstering of Hamas," the same source added.

Another Israeli concern is that agreeing to Fayyad's proposal may lead to an irreversible situation, making it impossible to use closures as leverage in response to Qassam rocket attacks.

"This will not solve a thing and the Qassams will continue to fall," the senior political source explained. "But then the closures will run into even more severe international reaction."

Pressure on Israel to end the blockade on the Gaza Strip intensified Monday, with Israeli ambassadors in many of the world's capitals being summoned to the local foreign ministries for clarifications on the situation.

Israel's actions in the Gaza Strip have been perceived, particularly in Europe, as an exercise in collective punishment.

Slovenia's Foreign Minister, Dimitrij Rupel, whose country currently holds the EU Presidency, talked with Foreign Minister Tzipi Livni and informed her of pressure to issue a statement on behalf of the EU condemning Israel.