Syrian rebels on Tuesday denied government claims that they had used chemical weapons, blaming President Bashar Assad's regime instead for the deadly rocket attack that caused "breathing problems."

"We understand the army targeted Khan al-Assal (in Aleppo province) using a long-range missile, and our initial information says it may have contained chemical weapons," mainstream rebel Free Syrian Army spokesman Louay Muqdad told Agence France Presse.

Syrian rebels on Tuesday seized a guard post near the Jordanian border and a tank brigade headquarters in the south of the country, after regime forces withdrew, a watchdog reported.

"They managed to seize control of a border post near Tel Shehab at dawn after regime forces evacuated the post following violent clashes," Rami Abdel Rahman, directer of the Syrian Observatory for Human Rights said.

Baghdad is "looking the other way" as Iran sends military equipment through Iraqi airspace to Syrian President Bashar Assad's regime amid the ongoing conflict in Syria, a U.S. official said.

The official, who spoke on condition of anonymity, called on Iraq to randomly search Iranian planes flying to Syria, and said Washington had complained to "all levels of the Iraqi government" about the lack of inspection.

A wave of attacks and explosions in Iraq killed 50 people on Tuesday and officials delayed provincial polls, highlighting security concerns on the eve of the 10th anniversary of the U.S.-led invasion.

At least 20 explosions and two assassinations also left more than 170 people wounded in the country's bloodiest day in more than six months, reflecting the brutal unrest and endless political crises that were sparked by an invasion that had aimed to build a democratic ally in the heart of the Middle East.

The international community must act quickly to stop Syria's "complete destruction," U.N. leader Ban Ki-moon warned Monday as the conflict entered a third year.

Condemning the "brutal force" used by President Bashar Assad's forces over the past two years, Ban said in an anniversary statement that "today the world is watching the consequences with horror" and those responsible must face justice.

U.N. Secretary General Ban Ki-moon on Monday congratulated the people and president of Yemen as a national dialogue got underway that will lead to the drafting of a new constitution and elections.

Ban "commends President Abdrabuh Mansour Hadi Mansour, the government and the people of Yemen for their determination and wisdom in keeping the transition process on track against many odds," the U.N. leader's spokesman said in a statement.

Syria's main opposition National Coalition early Tuesday elected Ghassan Hitto, a former U.S.-based IT executive with Islamist leanings, as prime minister for Syrian rebel-held territory.

In a new challenge to the regime of President Bashar Assad, the Coalition appointed Hitto after some 14 hours of closed-door consultations in the Turkish city of Istanbul.

The United States is struggling to track a fragmented Syrian opposition and has found it increasingly difficult to get a clear picture of rebel factions, the U.S. military's top officer said Monday.

"About six months ago we had a very opaque understanding of the opposition and now I would say it's even more opaque," General Martin Dempsey, chairman of the Joint Chiefs of Staff, told the Center For Strategic and International Studies (CSIS), a Washington-based think tank.

The Israeli parliament gave its seal of approval on Monday to Prime Minister Benjamin Netanyahu's new governing coalition, which includes a strong showing of pro-settlement hardliners.

A motion of confidence in the new administration, broadcast live on public television, gave it 68 votes in favor and 48 against.

A decade after the U.S.-led invasion of Iraq, Americans remain divided over the war, with a majority believing it was a mistake, according to a poll released Monday.

The Gallup survey, the first since U.S. forces withdrew from Iraq in December 2011, showed Americans are still split over the war, with 53 percent saying they regret the decision to invade and 42 percent saying it was not a mistake.