GENEVA, July 12 (Reuters) - The United Nations called on Tuesday for free movement and protection of civilians fleeing fighting in the South Sudanese capital of Juba, where it said at least 36,000 displaced people are seeking shelter in U.N. sites and other locations.

"Access to those in need is limited by the ongoing fighting and insecurity," U.N. spokeswoman Alessandra Vellucci told a news briefing in Geneva.

Access to the U.N. compound is being blocked for civilians, who are trapped in churches and schools without access to water and sanitation, the World Health Organisation (WHO) said, adding that it was sending trauma kits. Meanwhile the U.N. refugee agency called on neighbouring countries to keep their borders open to people seeking asylum and said it was gearing up for possible refugee outflows.

(Reporting by Stephanie Nebehay, editing by Tom Miles) ((Stephanie.Nebehay@thomsonreuters.com; +41 22 733 3831; Reuters Messaging: stephanie.nebehay.thomsonreuters.com@reuters.net; twitter @StephNebehay))