Syrian forces were locked in fierce gunfights Monday with rebels in one city and shelled another, as the U.N. chief urged "maximum restraint" after the arrival of observers to oversee a truce aimed at ending 13 months of bloodshed.

President Bashar al-Assad's forces killed at least 45 civilians and were fighting rebels at Idlib in the northwest, while also shelling the flashpoint central city of Homs, said the Local Coordination Committees and the Syrian Observatory for Human Rights.

The United Arab Emirates has summoned Iran's ambassador to Abu Dhabi to denounce a visit by President Mahmoud Ahmadinejad to a disputed island in the Gulf, the official state news agency said on Monday.

The UAE's minister of state for foreign affairs, Anwar Qarqash, "summoned the Iranian ambassador... and handed him a letter of protest, denouncing" Ahmadinejad's visit on Wednesday to Abu Moussa, WAM reported.

The first international observers tasked with monitoring a shaky U.N.-backed ceasefire arrived Sunday in Syria, where regime forces pounded a rebel city.

"They've arrived and they will start work tomorrow morning," said Kieran Dwyer, a spokesman for the U.N. peacekeeping department announcing that six observers were now in Syria.

Syrian Foreign Minister Walid Muallem will visit ally China at an unspecified date to discuss the mission of U.N.-Arab League envoy Kofi Annan who designed the ongoing fragile ceasefire in the country, Syria’s state-run news agency SANA reported on Sunday.

SANA said Muallem would go to China on a two-day visit at the invitation of his Chinese counterpart Yang Jiechi.

Iran has bought itself extra time during a first round of key talks with world powers over its disputed nuclear program, Israeli Prime Minister Benjamin Netanyahu said on Sunday.

"My initial impression is that Iran has been given a 'freebie'," Netanyahu said during talks with visiting U.S. Senator Joe Lieberman, the premier's office reported.

U.N. chief Ban Ki-moon voiced concern on Sunday over the Syrian regime's shelling of the central city of Homs and urged the government to do everything to maintain a fragile ceasefire.

"I am very much concerned about what has happened since yesterday and today," Ban said after talks with Belgian Prime Minister Elio Di Rupo in Brussels.

Libyan leader Mustafa Abdel Jalil, head of the council that overthrew Moammar Gadhafi, arrived in Algeria Sunday for a state visit that comes amid a period of strained relations.

Algerian President Abdelaziz Bouteflika and an entourage of senior government officials and foreign diplomats met Abdeljalil at the airport when he arrived around 4:00 pm (1500 GMT), an Agence France Presse photographer said.

Three children were among seven people killed on Sunday in Yemen's restive east and south by suspected al-Qaida militants, security officials said, after three jihadist suspects died in an air strike.

The defense ministry said in a statement on its website that three "local al-Qaida leaders" were killed in a Yemeni air strike late Saturday while a security official told Agence France Presse the raid was conducted by a U.S. drone.

Jordan's King Abdullah II on Sunday ordered the release of 19 political activists charged with insulting him during pro-reform demonstrations last month, a palace official said.

"The king instructed the government to take all necessary measures as soon as possible to release the jailed activists," some of them from the southern city of Tafileh, he told Agence France Presse.

Bomb attacks killed five people in Iraq on Sunday, including three members of a family whose house was blown up north of the capital, security officials said.

"Unknown gunmen planted three bombs around a house made of mud and reeds in the Taji area, causing it to completely collapse and killing a father, mother and five-year-old boy," an interior ministry official said.