UPDATED 5:48pm: The UN's humanitarian chief has said she is "extremely concerned" that Nepal's customs authorities are slowing the delivery of quake aid, and has urged the prime minister to fix the problem.

The death toll in Nepal from last weekend's devastating earthquake has risen to 7040.

More than 14,000 other people were injured when the 7.8-magnitude tremor struck. There are fears the death toll could rise.

There have been numerous reports of foreign aid getting stuck at Kathmandu's small international airport or even turned back at the border with India by customs officials.

"I was extremely concerned to hear reports that customs was taking such a long time. I was able to raise this with the prime minister this morning," Amos told AFP on Saturday at the end of a visit to Nepal after a 7.8-magnitude quake that has killed thousands and left many more homeless.

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."

Nepal's government has faced criticism for the slow pace of relief efforts, with many remote communities yet to receive any aid a week after the quake struck.

The country's only international airport has also struggled to cope, with flights carrying aid being turned away because there was no space to park the plane.

Amos said access to the airport was improving, and the UN was looking at bringing more aid into the landlocked country overland from India.

But she said much more needed to be done to reach quake victims in remote mountainous areas of Nepal, already one of the world's poorest countries even before the quake struck.
Some 6700 people are known to have died in the quake so far.