GENEVA, June 22 (Reuters) - The number of people needing humanitarian assistance in Syria has risen to 1.5 million from the previous estimate of 1 million as escalating violence drives more people from their homes, the United Nations said on Friday.

Aid agencies face "significant" constraints in reaching growing numbers of civilians who need basic goods and protection, it said.

"Up to 1.5 million people now need humanitarian assistance in Syria," Jens Laerke, spokesman for the U.N. Office for the Coordination of Humanitarian Affairs (OCHA), told a news briefing in Geneva.

They include 350,000 in northern Idlib province and some 250,000 in the flashpoint city of Homs, where more than 100 public buildings have been turned into temporary shelters for people who have fled their homes, an OCHA statement said.

The U.N.'S World Food Programme had distributed food to 461,000 Syrians by mid-June and aims to increase that number to 850,000 in July, the statement said.

The world body, which announced on June 5 that it had reached an agreement with Syrian authorities to implement a major assistance programme, has been stymied by the deteriorating security situation, according to Laerke.

Reconnaissance missions have been conducted and humanitarian hubs will be established initially in Homs and Deir al-Zor in the east. "However, given the deteriorating security situation, the deployment of staff to field locations is on hold", OCHA said.

More than 86,000 Syrian refugees have now been registered in Iraq, Jordan, Lebanon and Turkey - a rise of nearly 20,000 since May 31, it said, quoting the U.N. refugee agency UNHCR. (Reporting by Stephanie Nebehay; Editing by Alessandra Rizzo)

Earlier on HuffPost: