Supporters of Tunisia's ruling Islamist party on Tuesday attacked a demonstration by the country's main labor union, in the latest unrest two years after the revolution, Agence France Presse reported.

Several dozen assailants attacked members of the General Union of Tunisian Workers (UGTT) who were gathered outside the union's headquarters in Tunis to mark the 60th anniversary of the assassination of its founder, Farhat Hached.

The United States on Tuesday appealed for restraint on both sides in Egypt as supporters and opponents of President Mohamed Morsi clashed during nationwide protests.

"We would simply urge that protesters express their views peacefully and that they be given the environment, if you will, to protest peacefully," State Department spokesman Mark Toner said.

NATO on Tuesday agreed to deploy Patriot missiles along the border of member state Turkey as requested by Ankara to help it defend its territory against threats from Syria.

"NATO has agreed to augment Turkey's air defense capabilities in order to defend the population and territory of Turkey and to contribute to the de-escalation of the crisis along the alliance's border," a statement said.

Russian Foreign Minister Sergei Lavrov warned Tuesday that deploying Patriot missiles along Turkey's border with Syria risked pouring more arms into the region, and dismissed fears of Damascus using chemical weapons.

Russia recognized Turkey's right to ask for help from its NATO allies, Lavrov said, but added: "We are concerned that the conflict is being increasingly militarized."

Tens of thousands of Egyptian demonstrators Tuesday encircled the presidential palace after riot police failed to keep them at bay with tear gas, in a growing crisis over President Mohamed Morsi's decree widening his powers.

The protesters cut through barbed wire a few hundred meters (yards) from the palace, prompting police to fire the tear gas before retreating, allowing demonstrators to reach the palace walls, Agence France Presse reported.

Egypt's foreign ministry on Tuesday summoned Israel's ambassador to Cairo, Yaakov Amitai, to issue a "strong protest" over the Jewish state's plans for new settlements, a ministry spokesman said.

Alaa Eldine Yussef, who heads the Israeli affairs section at the ministry, told the envoy that "the Israeli government's plan contradicts the concept of land for peace, on which peace efforts in the region are built," spokesman Amr Roshdy said.

The influence of hardline Islamists is increasingly being seen on Syria's battlefields, with even the more secular rebel fighters starting to sport jihadist-style beards, headbands and clothes.

The trend is confusing the West and complicating the dispatch of aid, especially weapons, to the insurgents, experts say.

Iraq on Tuesday barred Turkish Energy Minister Taner Yildiz's plane from landing in Arbil, capital of the autonomous Kurdistan region, in the latest sign of worsening ties between the once-close neighbors.

The incident highlighted chilly ties between Baghdad and Ankara, in part due to issues related to Iraqi Kurdistan, and rows between the Iraqi federal government and the Kurds over energy contracts and disputed territory.

France on Tuesday joined the United States and NATO in delivering a blunt warning to Damascus not to use chemical weapons on rebels, warning that the international community would react if it did.

"Any use of these chemical weapons by (Syrian President Bashar) Assad would be unacceptable," foreign ministry spokesman Vincent Floreani told reporters.

Activity around Syria's chemical weapons is ringing alarm bells in Washington and other world capitals, but secrecy surrounding the stockpile makes it difficult to gauge its nature and size.

U.S. President Barack Obama on Monday warned Syrian President Bashar Assad "there will be consequences" if he unleashed those weapons in the civil war wracking his country.