Representatives of more than 100 countries and organizations were converging here on Wednesday to discuss Syria's 21-month conflict and ways to support the opposition seeking to overthrow President Bashar al-Assad, dpa reported.
The Friends of Syria conference is being held a day after the United States formally recognized the main Syrian opposition alliance, which is hoping to seek broader recognition in Morocco.
Britain, France, Turkey and Gulf countries have already recognized the National Coalition for Syrian Revolutionary and Opposition Forces, launched last month to present a united front against al-Assad and led by Moaz al-Khatib.
"Topping the agenda of the Marrakesh conference is the humanitarian situation in Syria, as the numbers of Syrian refugees are soaring," George Sabra, the head of opposition Syrian National Council, told dpa.
The foreign ministers of France, Britain and Canada are attending the meeting. US Secretary of State Hillary Rodham Clinton cancelled her visit due to health reasons.
In Syria, battles were Wednesday raging between government troops and rebel fighters on the outskirts of the capital Damascus, reported the Syrian Observatory for Human Rights, an activist group.
In the central province of Hama, activists reported that at least 125 civilians had been killed or wounded in an attack on Tuesday targeting members of al-Assad's minority Alawite sect. It is not clear who was behind the attack.
Human Rights Watch said Wednesday that the Syrian military had used air-delivered incendiary bombs in at least four locations across the country since mid-November.
"We're disturbed that Syria has apparently begun using incendiary munitions, as these weapons cause especially cruel civilian suffering," said Steve Goose, the director of arms division at the group.
Independent verification of reports coming out of Syria is hampered by government restrictions on the movement of journalists.