* UN struggling to help Syrians in civil war, refugees
* U.S. has given total of $365 mln to Syria, is largest single donor
* UN has said it has raised only 3 pct of the $1.5 bln it needs
By Roberta Rampton
WASHINGTON, Jan 29 (Reuters) - President Barack Obama on Tuesday said the United States would boost humanitarian aid to Syria and urged other nations to do more to help the United Nations, which is struggling to assist some 4 million people in the war-torn country and more than 700,000 who have fled it.
Obama said he authorized an additional $155 million in aid for food, medical care and clothing for Syrians and refugees, bringing the U.S. total to $365 million. He issued a video statement on youtube.com with Arabic subtitles speaking directly to Syrians. [http://link.reuters.com/fax55t ]
Obama has been criticized for not doing more to aid rebels trying to overthrow Syrian President Bashar al-Assad, even as the humanitarian cost of the conflict has skyrocketed and Western nations worry about the growing clout of Islamic militants among the rebels.
Obama has said he has wrestled with whether a U.S. military intervention in Syria's 22-month-old civil war would help resolve the bloody conflict or make things worse. The United Nations said more than 60,000 people have died in the uprising.
On Tuesday, he said the aid would help bring food and clean water to Syrians. "It means immunizations for 1 million Syrian children," Obama said in a statement. "American aid means winter supplies for more than half a million people in Aleppo, Homs and Dayr az Zawr."
The United Nations has said it needs about $1 billion to help refugees and another $519 million to help people inside Syria but on Monday it had raised only 3 percent of that target.
"Today I also call on the international community to do more to help these Syrians in need and to contribute to the latest U.N. humanitarian appeal," Obama said.
The United States is the largest single aid donor in the crisis but the assistance has been provided quietly, said White House spokesman Jay Carney.
"It is a cruel fact that human aid providers and recipients are being deliberately targeted in Syria," Carney told reporters. "Our priority is to get American aid to those who need it without endangering them or our humanitarian partners." (Reporting by Roberta Rampton; Editing by Bill Trott)