(CNN) -- An Algerian diplomat has been appointed to replace Kofi Annan as the special U.N. and Arab League envoy to Syria.

He is Lakhdar Brahimi, Eduardo Del Buey, the spokesman for U.N. Secretary-General Ban Ki-moon, said Friday. Brahimi previously was a special U.N. representative in Iraq and Afghanistan.

"The violence and the suffering in Syria must come to an end. The secretary-general appreciates Mr. Brahimi's willingness to bring his considerable talents and experience to this crucial task for which he will need, and rightly expects, the strong, clear and unified support of the international community, including the Security Council," Del Buey said.

"Diplomacy to promote a peaceful resolution to the conflict in Syria remains a top priority for the United Nations. More fighting and militarization will only exacerbate the suffering and make more difficult the path to a peaceful resolution of the crisis, which would lead to a political transition in accordance with the legitimate aspirations of the Syrian people."

Principal deputy White House press secretary Josh Earnest said "Brahimi is a capable and seasoned diplomat, well-known to us and others in the international community.

"We look forward to continuing to work closely with the U.N. to support an end to the bloodshed in Syria, and the advancement of a Syrian-led and internationally supported political transition."

Brahimi's selection came as Western and Arab diplomats gathered at the United Nations to try to plot an end to a civil war that has left thousands dead and as many as 2.5 million more in dire need of humanitarian aid.

There had been talk of the appointment, and Syrian Foreign Minister Walid Moallem told Syrian State TV late Thursday that President Bashar al-Assad's regime welcomed the pick.

Ban vowed Thursday to keep a presence in Syria, possibly opening a liaison office that would support efforts for a political solution to the crisis.

While Ban did not disclose the size of the operation, a spokeswoman for the U.S. State Department told reporters it would be a relatively small contingency of about 20 people.

Annan recently announced he was stepping down after his negotiated peace deal failed to take hold. The U.N. Security Council is pulling its 300 observers who were in Syria to monitor the failed peace plan.

As diplomats worked to find a political solution, fighting raged across Syria. At least 140 people were killed, including 36 in Aleppo and 35 in Damascus and its suburbs, a figure that includes 16 young men who were slaughtered in Douma, the opposition Local Coordination Committees of Syria said.

There were 30 other deaths in Daraa, including eight bodies that were burned in Nawa; and 23 in Homs, including 10 in Deir Baalba and an entire family from Qosair.

For days, the city of Aleppo in northern Syria has been the center of some of the worst fighting.

The opposition also accused Syrian forces of shelling flashpoint neighborhoods in Aleppo where rebels are making a stand, according to the Syrian Observatory for Human Rights, a London-based opposition group.

It is the latest hotspot in a nearly 18-month conflict that began in March 2011 with a brutal government crackdown on mass protests calling for government reform. The protest movement quickly devolved into an armed conflict.

Al-Assad's government has refused to acknowledge the civil war, maintaining it is fighting armed gangs and foreign fighters bent on destabilizing the country.

"Some may ask why there is a delay in Aleppo, and I will say it is simple. The Syrian military has plans to keep the casualties and the destruction of the infrastructure to its minimum when confronting these armed gangs," Moallem told State TV.

"The Syrian military always keeps in mind that they need to safeguard and protect everyone. But the armed terrorist gangs have no principles, they kill and destroy and no one holds them accountable."

CNN is unable to independently verify claims of violence as Syria has severely restricted the access of international journalists.

Despite the claims, the humanitarian situation in Syria appears to be deteriorating rapidly.

Syrians continue to flee to the neighboring countries of Jordan, Lebanon, Turkey and Iraq, the U.N. refugee agency said Friday. More than 170,000 Syrian refugees in those countries have been registered by the United Nations, it said.

"The real number of refugees is higher as not all refugees register," the agency said.

Many Iraqis who took refuge in Syria because of the war in Iraq have gone home.

"The total number of Iraqi returnees from Syria has reached 26,821 since July 18, including 5,997 returnees by air," the agency said.

"Over a million people have been uprooted and face destitution. Perhaps a million more have urgent humanitarian needs due to the widening impact of the crisis on the economy and people's livelihoods," Valerie Amos, the U.N. under-secretary-general for humanitarian affairs, told reporters in Damascus on Thursday.

CNN's Ben Wedeman in western Syria and Saad Abedine and Joe Sterling in Atlanta contributed to this report.