Caritas Australia's Indian and Nepalses partners have begun helping in the "worst flooding in 100 years" in India's Karnataka and Andhra Pradesh states, and in Nepal's Accham and Dadeldhura districts where rains triggered landslides.
An estimated 250 people have been killed and more than 2.5 million people are homeless in the Indian crisis, while some 45 are confirmed dead in the Nepal landslides, Caritas said.
"Like in South East Asia after Typhoon Ketsana, we need swift assistance for the displaced and immediate steps to combat an influx of water borne diseases. In the acute emergency phase our local partners will be assessing where the greatest need is and focusing our assistance there. Temporary shelter will be required and the threat of polluted water poses great risk for those temporarily displaced," said Caritas Australia's CEO Jack de Groot.
With the monsoon beginning in India further flooding is expected. Current rains have submerged villages.
Caritas Australia is accepting donations for their relief work in the region.
Meanwhile, Australia's Bishop Peter Ingham, who is attending the Synod of Bishops currently being held in Rome in his capacity as President of the Federation of Catholic Bishops Conferences of Oceania, has appealed for prayers for the victims of the disasters in Samoa and Tonga.
"As global temperatures and ocean waters rise, always the poorest and most vulnerable will suffer disproportionately, as they do from drought, flooding and poor harvests, all of which can stir up reasons for conflict and give rise to massive migration by refugees and asylum seekers," he said.
"In both Oceania and Africa, great work is being done by the Church and its agencies to help people recover their equilibrium in their communities and to manage risks that could arise from natural disasters. We can and must learn from one another.
"I ask your prayers for Samoa and Tonga in their grief after the recent earthquake and tsunami."
Caritas prepares for new disaster front in Asia Pacific with Indian floods (Caritas)
Bishop Ingham asks Synod Bishops in Rome to pray for the people of the Pacific (ACBC)
Synod reports from 5 continents (Zenit)