UNITED NATIONS -- The U.N. secretary-general said Thursday that he will launch an investigation into whether chemical weapons were used in Syria, seeking to address accusations that, if proved, could alter the trajectory of the two-year civil war in the country.
Speaking to reporters at the U.N. headquarters in New York City, Secretary-General Ban Ki-moon said his top advisers are still trying to determine the scope of the mission and steps required to guarantee the safety of U.N. personnel during the probe.
Their immediate task will be to investigate an attack Tuesday near the city of Aleppo, in which both the Syrian government and the opposition claimed that the other side had used chemical weapons. But Mr. Ban hinted that the team's mandate could be broader, saying he hoped that the mission "would contribute to ensuring the safety and security of chemical weapons stockpiles in Syria."
The Obama administration, which has said any Syrian government use of chemical weapons would be a "red line," signaled support for such a wide-ranging investigation. U.N. Ambassador Susan Rice said U.S. officials back an investigation that "pursues any and all credible allegations of the possible use of chemical weapons in Syria."
The U.N. announcement came amid signs that the Syrian war, which has killed more than 70,000 people, is threatening to spiral further into a regionwide crisis. This week, a top U.N. official said 3.6 million people had been internally displaced during the conflict, and that 1.1 million had registered as refugees in the four neighboring countries.
The war is also threatening the 39-year-old cease-fire between Syria and Israel, as fighting undermines international peacekeepers' capacity to monitor the separation line between the two countries. Mr. Ban has warned the Security Council that Syrian armed forces have crossed into the U.N.-monitored demilitarized zone in pursuit of rebel groups using the area as a haven. The breaches represent a "grave violation" of the cease-fire, he said in a letter, a copy of which The Washington Post obtained.
Violence in Syria, meanwhile, has been unabating. On Thursday, a bombing at a mosque in the capital, Damascus, killed 42 people, including a senior Sunni cleric, according to Syrian media reports and opposition groups. Mohammed Said Ramadan al-Bouti was imam of the nation's largest, most important Sunni mosque and known for backing President Bashar al-Assad.
The attack that is the immediate focus of the U.N. inquiry occurred in Aleppo province and is said to have killed 26 people, including 16 Syrian soldiers. There has been no independent confirmation that chemical weapons were used, nor has there been confirmation that such munitions were used in other recent cases, as alleged by the opposition.
An Obama administration official said ongoing analysis of the incident indicates that it probably did not involve chemical weapons.