More than 600 people have died as a result of floods in India and Pakistan, a regional expert for Tearfund has confirmed.
Flash floods, which began on September 3, have triggered landslides, putting at least half a million people in immediate danger.
Thousands of homes have been destroyed in the neighbouring countries, along with vital infrastructure, communication equipment and crops.
Pakistani and Indian troops have been evacuating victims and making food drops with helicopters, but the BBC's Andrew North reports that "a surge of water flowing from across the border in India" is currently causing significant concern.
Prime Ministers Narendra Modi and Nawaz Sharif have offered to help one another, though much of the flooding is in the Kashmir region – which is divided between India and Pakistan and a source of contention between the two nations– making the situation even more complicated, AP reports.
A spokesperson for the Pakistani National Disaster Management Authority said more than 190 people have been killed in Punjab province and the Pakistani-administered part of Kashmir.
Water levels reportedly rose up to 18 feet at some points of the Jhelum River in Indian-administered Kashmir when it breached its banks, and the death toll now stands at over 150 in Jammu and Kashmir state.
"In Kashmir, the area where the flooding has been the worst, over 600 people have died, both on the Indian and Pakistani sides," Tearfund's head of Asia region, Sudarshan Sathianathan, told Christian Today.
"We've heard [from partner organisations] that this number is likely to increase simply because some of the remote areas have not yet been visited, and only when we get there will we realise quite what the situation is."
Sathianathan also warned that the outbreak of disease such as cholera is imminent due to lack of clean water and sanitation.
"We must hope and pray that the rains aren't too heavy, but the reality is that this is the beginning of the monsoon season, so we're likely to see more flooding," he added.
"At the moment, here in the UK the media is focused on the Middle East, Africa and the Scottish referendum, so it's unlikely that the flooding in Asia will reach people's attention. But it's very important to pray that the needs of these people will be addressed locally, and that local governments will use the resources they have to reach out to the people in greatest need."