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.

A rebel mortar attack on a school in a camp for displaced people near Damascus on Tuesday killed nine students and their teacher, Syrian state television reported, branding it a "horrific crime."

The broadcaster also reported 20 people were injured in the attack, but it was not immediately possible to verify their identities.

Saudi Arabia's Foreign Minister Prince Saud al-Faisal on Tuesday received a delegation from the new Syrian opposition bloc, the National Coalition, headed by its chief Ahmed Moaz al-Khatib, the Saudi state news agency SPA reported.

They discussed "developments in Syria and all ongoing international efforts on this matter."

Any use by the Syrian regime of chemical weapons against its own people would spark an immediate reaction by the international community, NATO head Anders Fogh Rasmussen warned Tuesday.

"The possible use of chemical weapons would be completely unacceptable to the whole international community and and I would expect an immediate reaction from the international community," Rasmussen said.

Gunmen armed with silenced weapons attacked a house in east Baghdad on Tuesday, killing a man, his wife and four children, a security official and a medic said.

The attack took place in the Zayouna area, an interior ministry official said, adding that the motive for the crime was not known.

Egyptian independent and opposition newspapers refused to publish their Tuesday editions in protest against lack of press freedom in the country's draft constitution, set for a popular referendum on December 15.

The move was in order to "stand up to tyranny," independent daily Al-Tahrir said on its website.

A Syrian journalist working for a government newspaper was killed in a south Damascus neighborhood on Tuesday, state television announced.

"An armed terrorist group assassinated the journalist Naji Assaad in the Tadamun district of Damascus as he was on his way to the Tishreen newspaper," the broadcaster said.

The Syrian army shelled several areas east and southwest of Damascus early Tuesday hours after radical Islamist fighters seized a village in an eastern province bordering Iraq, a watchdog said.

"The army shelled the orchards in the Eastern Ghuta region (east of the capital), as it pressed on with its military campaign in the area," said the Britain-based Syrian Observatory for Human Rights.

Jordan's King Abdullah II arrives in Ramallah on Thursday on his first visit since the Palestinians won U.N. recognition as a non-member state, a senior official told Agence France Presse on Tuesday.

"King Abdullah will visit the state of Palestine the day after tomorrow, on Thursday, in the first visit by a top official to the Palestinian state after we received U.N. recognition," said Nimr Hammad, political adviser to Palestinian president Mahmoud Abbas.

Iran on Tuesday brushed away a renewed call from the United Arab Emirates for the two countries to resolve through discussion their vying claims to three strategic islands in the Gulf.

"Repeating baseless claims will not have any influence on existing realities. The three Iranian islands have been and will remain an integral part of the Islamic Republic of Iran's territory," Iran's foreign ministry spokesman Ramin Mehmanparast said in a statement.