Lebanon's prime minister called Israel's blockade of the country illegal on Saturday and the parliament speaker urged Arab nations to break the siege.

The calls, however, were not expected to make Israel relent in its refusal of European and U.N. requests to end its blockade of Lebanon's air and seaports. But the effort heightens tension that could further upset the already shaky cease-fire.

Israel says the restrictions are necessary to prevent Hezbollah from rearming until U.N. troops guard the borders. Lebanon says they hamper the delivery of food and medical supplies and attempts to revive the country's battered economy.

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Speaking to a special parliament session, Prime Minister Fuad Saniora condemned the "unjust, illegal blockade" and said his government is sparing no effort to lift the siege.

The Western-backed Saniora rejected the contention that the blockade was being carried out under paragraph 14 of the U.N. Security Council cease-fire resolution, which calls on the Lebanese government to secure its borders and other entry points to prevent the influx of weapons.

"Who assigned Israel to be guardian of the implementation of the resolution?" Saniora asked.

Parliament Speaker Nabih Berri said the parliament plans to send a letter to Arab governments to "ask and insist that all Arab planes and ships break the blockade without seeking any permission from Israel."

Berri, a Hezbollah ally who wields significant influence in the government, described the blockade as "a military aggression that is an attack on national sovereignty and a clear violation of resolution 1701" which ended 34 days of fighting between Israel and Hezbollah.

Berri announced a series of protest measures. Envoys were to encourage Arab states that have diplomatic ties with Israel to reduce them and will ask others to put economic dealings with Israel on hold. Arab nations also would be asked to seek U.N. Security Council action.

"We are not asking for the severing of diplomatic ties, but at least the withdrawal of envoys, and an end or freezing of economic ties with Israel as long as there is a blockade of Lebanon," said Berri.

Jordan, Egypt and Mauritania have full diplomatic ties with Israel. Several others are believed to quietly conduct business with the Jewish state.

Berri said parliament will also send letters to legislatures around the world and that Lebanese lawmakers would meet with envoys of the five permanent members of the U.N. Security Council to implore them to work for the lifting of the blockade.

The speaker launched an open-ended sit-in by parliamentarians to protest Lebanon's plight during which they intend to take turns -- 10 at a time -- staying overnight in the building in downtown Beirut.

Berri warned there could be more action, including a possible attempt by Lebanese aircraft to break the blockade that has continued despite the Aug. 14 cease-fire.

"If they continue (the blockade) we will step up the action," Berri warned. "If we have to, then come what may."

Currently, Israel allows only Lebanese and Jordanian commercial flights to land in Beirut, on condition they make a stop in Amman before proceeding to the Lebanese capital. It has permitted flights carrying food and medical supplies to land in the Lebanese capital. Ships cleared by the Israelis are allowed entry to Lebanese seaports.

U.N. Secretary-General Kofi Annan has called for an end to the blockade, but was rebuffed by Israeli Prime Minister Ehud Olmert last week on a visit to Israel.

Israel has said it will only lift the blockade after Lebanese borders and points of entry are secured. Israeli officials want U.N. troops deployed along Lebanon's border with Syria. But Damascus rejects that as a hostile act and reportedly threatened to close its border, Lebanon's only land link to the Arab world, if an international force is deployed.

The Lebanese government has deployed thousands of troops on the border with Syria, a key Hezbollah ally.

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