NAIROBI - The United Nations has called for unrestricted access to millions of Somalis in need of aid, amid attacks on U.N. compounds and threats to shut down U.N. agencies from hardline Islamist group Al Shabaab.

Al Shabaab gunmen looted two U.N. offices on Monday, after the al Qaeda-linked militants said UNDP (United Nations Development Programme), UNDSS (United Nations Department of Safety and Security) and UNPOS (United Nations Political Office for Somalia) were working against Somali Muslims and the establishment of an Islamic state.

"We are hopeful that all groups in Somalia will accept and acknowledge the importance of humanitarian action and we will have unhindered access," Rozanne Chorlton, acting U.N. humanitarian coordinator for Somalia, told Reuters Television.

An upsurge in violence since May has killed nearly 200 people in Mogadishu and forced some 223,000 residents from their homes - about 20,000 in the past two weeks alone. Nearly half of Somalia's population - 3.4 million people - depends on food aid.

"We are concerned that everybody has the correct understanding of what the U.N. is doing in Somalia - that our intentions and our actions are designed to give relief and well-being to the people of Somalia. We have no other agenda behind that," Chorlton said.

The offices attacked were in Baidoa - the seat of Somalia's parliament before insurgents seized the town - and the World Food Programme's (WFP) compound in Wajid in the Bakool region.

"The compounds in Wajid and Baidoa were entered by militia yesterday. In both instances, items were taken - in Wajid, less so and really not in a way that really our operations have been interrupted," said Chorlton.

"In Baidoa, on the other hand, we have lost quite a lot of equipment, including vehicles, and especially what is concerning us...is the removal of our radio communication equipment because we cannot conduct any humanitarian action - even life-saving operations - without (this) equipment," she added.

Al Shabaab controls much of southern Somalia and parts of the capital Mogadishu, and is fighting government troops and African Union peacekeepers to impose its own harsh version of sharia law throughout Somalia.

It is resisting a push by President Sheikh Sharif Ahmed's security forces to chase its fighters from the capital, and in rural areas, it is fighting a moderate, pro-government Islamist militia, with towns and territory often changing hands between the two sides.

U.N. OPERATIONS HAMPERED

On Monday, a U.N. official said expatriate staff in Baidoa were being evacuated to neighbouring Kenya, but operations in Wajid would continue as minimum security conditions had not been affected.

The United Nations in Somalia said in a statement it was re-assessing the situation on the ground, but expected local authorities to reconsider their decisions and allow its agencies to address the critical humanitarian situation in the Baidoa region.

Al Shabaab said other non-governmental organisations and foreign agencies operating in Somalia should contact the administration in their area to find out about conditions and restrictions on their work.

The U.N. refugee agency (UNHCR) said on Tuesday this week's incidents had brought most of its assistance efforts in the neighbouring region to a halt.

It added that the worsening security situation is hampering the delivery of assistance from the port of Mogadishu to Afgooye - where many of those displaced from Mogadishu are sheltering in sweltering makeshift camps - and other parts of Somalia. For example, a distribution of 4,000 aid kits in and around Mogadishu, planned for this week, had to be postponed due to security concerns.

More than a dozen aid workers have been killed in Somalia since the beginning of 2008, but recent attacks have focused on U.N. assets.

Last month, the U.N. Children's Fund (UNICEF) said it was disturbed by a new wave of hostilities against humanitarian aid work in the country after Al Shabaab militia took over its compound in the central town of Jowhar in May, looting and destroying aid supplies and equipment.

"We are witnessing and experiencing an unprecedented level of aggression against humanitarian work in Jowhar, a situation that should cause a great deal of concern not only to the aid community but primarily to Somali communities," said Hannan Sulieman, acting UNICEF Somalia representative, in a statement.

"Perpetrators of these unacceptable and irresponsible actions must understand that their actions have serious consequences on their own children and women, their own communities and people."

The U.N. refugee agency says local humanitarian organisations are overstretched and struggling to meet the basic needs of those who have been newly displaced.

The agency reports a lack of adequate shelter, sanitation facilities and clean drinking water, and warns the situation has worsened following recent torrential rains.

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