WASHINGTON, Dec. 17 (Xinhua) -- The Obama administration on Monday voiced its "deep concern" about the reported deaths of dozens of civilians following the outbreak of armed conflict a day earlier in a Palestinian refugee camp in the Syrian capital Damascus.

"The United States is deeply concerned by reports that dozens of civilians, including women and children, were killed or wounded in Yarmouk, an area of Damascus home to 150,000 Palestinian refugees, as a result of aerial bombardment and fighting between Syrian government forces and armed opposition on Dec. 16," State Department spokeswoman Victoria Nuland said in a statement.

"These latest attacks mark a significant and alarming escalation of the conflict in Syria," she added, calling on all parties to stop "unlawful attacks on civilians and comply with international law."

On Sunday morning, more than 300 fighters from Nusra Front, an offshoot of the al-Qaida in Iraq, infiltrated the Yarmouk camp and clashed with local groups, causing loss of lives and exodus of inhabitants, local media reported.

The Palestinian Popular Front for the Liberation of Palestine General Command in the camp called on all Palestinian resistance factions to join forces to expel al-Qaida-linked terrorists from the area and thwart attempts to draw the Palestinians into the 21- month-long conflict in Syria.

"In addition to the suffering endured by the Syrian people, the United States is concerned about the situation of the more than 500,000 Palestinian refugees in Syria who are also increasingly suffering from the escalating violence," Nuland said.

"Those who are responsible for atrocities against the civilian population must be held accountable," she added.