The head of the Swiss Humanitarian Aid Unit says logistical difficulties are hampering relief operations for the victims of the earthquake in Pakistan.
Toni Frisch said last Saturday's quake had been devastating for the remote Himalayan region.
Frisch, who leads the humanitarian-aid section at the Swiss Agency for Development and Cooperation (SDC), said many villages in remote mountain valleys were still cut off, because roads and bridges had been destroyed by the quake.
Speaking in Mansehra after a flight over the Kashmir region on Thursday, Frisch said the logistical problems for the relief organisations had been underestimated.
He said the Swiss Humanitarian Aid Unit had hired mules and donkeys to transport emergency supplies.
Another concern for aid workers was the cold temperatures and snow.
Frisch said the quake had wreaked havoc in large parts of the Kashmir region and it was still difficult to assess the situation nearly a week after the earthquake.
"The cooperation with the Pakistani armed forces, local aid agencies, the United Nations and the Red Crescent Society has been excellent," he added.
He praised the local population for their extraordinary efforts to help the victims.
For the time being Swiss aid efforts were focusing on providing aid, notably tents, blankets and unpolluted water, for the hundreds of thousands of displaced people, said Frisch.
He added that Swiss relief operations would continue for several weeks.
Meanwhile, the Swiss-run International Committee of the Red Cross (ICRC) says it is providing assistance for 45,000 families affected by the earthquake in India and Pakistan.
The ICRC also set up an emergency hospital with 100 beds in the Pakistani city of Muzaffarabad.
A spokesman in Geneva said drinking water, food and shelter were a priority alongside medical supplies.
swissinfo with agencies
The Swiss Humanitarian Aid Unit is a militia corps with a pool of at least 700 people ready for duty.
It is divided into professional groups according to their knowledge and abilities.
Most experts are involved in humanitarian aid operations of the Swiss government. Others are active for international organisations, including the ICRC.
The earthquake measuring 7.6 on the Richter scale hit Pakistan and parts of India and Afghanistan on Saturday.
Estimates put the death toll in Pakistan as high as between 30,000 and 40,000. Officially it is 23,000. In India it is up to 1,300.
The UN has launched an appeal for $272 million over six months.