One week on from Nepal's devastating earthquake which keilled more than 6,700 people, Nepal ruled out finding more survivors on Saturday and shifted the focus to reach survivors in remoted areas who have yet to receieve relief supplies.The UN children's fund UNICEF warned of a race against time to avert an outbreak of disease among the 1.7 million youngsters estimated to be living in the worst-hit areas, with monsoon rains just a few weeks away.The 7.8-magnitude quake wreaked a trail of death and destruction when it erupted around midday last Saturday, reducing much of Kathmandu to rubble and even triggering a deadly avalanche on Mount Everest."It has already been one week since the disaster," home ministry spokesman Laxmi Prasad Dhakal told AFP."We are trying our best in rescue and relief work but now I don't think that there is any possibility of survivors under the rubble."As well as updating the death toll to 6,621, Dhakal put the number of injured at 14,023. More than 100 were also killed in India and China.While multiple teams of rescuers from more than 20 countries have been using sniffer dogs and heat-seeking equipment to find survivors in the wreckage, no one has been pulled out alive since Thursday evening.Nevertheless, relatives of those missing have refused to abandon hope."I believe he must still be trapped and will be rescued alive," said Suntali Tamang, whose husband Langte, 41, was believed to be in the same neighbourhood of Gongabu where the last survivors were found."I reached here three days ago after he went missing," she told AFP after travelling to Kathmandu from the family's home in the northeastern Dolakha district."He was the family's breadwinner and I am praying for him to be brought back safely."The exact scale of the disaster was still to emerge, with the mountainous terrain in the vast Himalayan nation complicating the relief effort.With relief workers still to reach many areas, it is likely to be some time before authorities come up with a comprehensive list of people missing but police said the task of compiling names had begun.The list so far only contained 204 names, national spokesman Kamal Singh Bam told AFP, as relatives had only just started approaching authorities."We have only just begun to draw up the list, the number will obviously go up," added the spokesman.UN aid chief Valerie Amos on Saturday said she was extremely concerned that Nepal's customs authorities were slowing the delivery of aid. Amos said she had reminded Prime Minister Sushil Koirala that Nepal had signed an agreement with the United Nations in 2007 that provides for simpler and faster customs clearance for relief aid in the event of a disaster."He has undertaken to ensure that happens, so I hope that from now we will see an improvement in those administrative issues," she told AFP.In Sri Lanka, visiting US Secretary of State John Kerry said the United States had provided $22.5 million in aid relief to Nepal.