Rescue workers are heading from the UK to Pakistan to help in the search for victims of an earthquake feared to have killed more than 3,000 people.
The earthquake has affected a vast area in South Asia
Anxious relatives are also preparing to fly out to the region in the hope of finding family members alive.
Foreign Secretary Jack Straw announced an initial aid package from the UK to help people affected by the earthquake.
The government is donating £100,000 and sending around 50 relief workers to provide aid in the region.
Search and rescue teams from Grampian, Lincolnshire, Greater Manchester and Lancashire were due to leave on Saturday evening.
A second flight with staff and emergency supplies, such as blankets, is due to leave from East Midlands airport.
Search for relatives
Many British Kashmiris have expressed frustration at being unable to get through to relatives and one charity said the community was "shocked and devastated".
Relatives are now preparing to fly out to the region after the Pakistan High Commission announced it would open its central London office and provide visa facilities at Heathrow, Birmingham and Manchester airports.
Fasil Ali, 27, a civil engineer from London, is one of 10 family members flying out from Heathrow to Pakistan to look for relatives.
He said he had spoken to some family members in Islamabad, but had not managed to reach those in Muzaffarabad, in Pakistani-controlled Kashmir - an area devastated by the quake.
Mr Ali said: "The ones in Islamabad we have heard from but we have not heard from those in Kashmir.
"The whole area is ruined. The big problem is no communications."
Mr Ali's uncle, 52-year-old Ajaz Hussein, from Luton, who is also flying to the area, said: "We are all very worried."
Mr Hussein added: "A large proportion of people in the Muslim community in Luton are from Kashmir. So there are many people like us worrying about their loved ones."
Anxiety and shock
The 7.6-magnitude quake hit Pakistan, Afghanistan and northern India, wiping out several villages in Kashmir.
Mr Straw, who is MP for Blackburn, in Lancashire, said the disaster would have a strong impact on British communities.
"All of us are shocked whenever news like this comes through, wherever the disaster is taking place.
"But in this particular case, because so many people in this country - so many of my own constituents - hail from Pakistan, or their families do, of course the anxiety and the shock is even greater," he said.
"My message to them is that we're going to do - and we are doing - everything we can for British people of Pakistani heritage, number one, and two, for Pakistanis of whatever connections."
Earlier Mr Straw said the government was "ready to respond to all requests", adding there was so far no news of any British casualties in the region.
Ishfaq Ahmed, chief executive of the Kashmir International Relief Fund, London, said the feeling among Kashmiri communities in Britain was "total devastation".
Mr Ahmed said: "The reason is not being able to get through to Kashmir. At the moment we have no idea of what is going on. We can't get through to any city."
He added the fund was setting up a public appeal to send aid into the region.
Prayers were said at Birmingham Central Mosque
Parveen Khan, 31 from North London, originally from Rawalakot in the Poonch district in Kashmir, told the BBC News website of her shock.
She said: "We really don't know anything. We are trying to get in contact with friends and family, but we can't get through.
"My family's house is in a small village in a very hilly area, it's very remote and they have little access to resources. It just happened so quickly, it's just such a shock.
"I don't think anything has happened there on this scale before. There might have been small tremors but nothing to this extent at all."
Defence Secretary John Reid, who returned from the area on Friday, expressed "shock and regret" at the disaster.
"Having returned from this region only yesterday, following a visit designed to strengthen our countries' work on counter-terrorism, my thoughts and sympathies are with all those affected by this tragedy," he said.
"I am grateful and relieved that UK troops supporting the reconstruction of Afghanistan have been unaffected by the earthquake," he added.
The earthquake struck at about 0850 local time (0450 BST). Its epicentre was 80km (50 miles) north-east of the Pakistani capital, Islamabad.
Oxfam's humanitarian response co-ordinator in Islamabad, Raphael Sindaye, said the charity "will be mobilising its existing partners and resources in the response".
He said: "The initial needs appear to be tents, blankets, medical kits, food aid, water and trauma counselling for those affected".
The charity's earthquake response co-ordinator, Jane Cocking, said the UK-based charity was meeting other aid agencies and the UN to co-ordinate a response.
London-based relief agency Muslim Aid said it had made £100,000 immediately available in the wake of the tragedy.
Treasurer Chowdhury Mueen-Uddin said: "Our field officer, Syed Muaijuddin, is on his way with a team of volunteers to the worst affected area, Muzaffarabad in Kashmir, with relief supplies.
"Further funds will be made available once the situation becomes more clear."