The International Federation of Red Cross and Red Crescent Societies said its appeal for 40 million Swiss francs ($51.5 million) would help support five million people through the next 16 months.

"Across the country, communities are facing growing humanitarian needs related to health care, shelter, water and sanitation, and mental health and psychosocial support," the IFRC said.

The funds will help the national Iranian Red Crescent Society (IRCS) to prioritise those directly affected by the war, and deal with infrastructure damage and disruptions to essential services.

"With humanitarian needs growing sharply with every passing day, this emergency appeal will help scale up lifesaving assistance and get support to those most affected," Maria Martinez, the IFRC's delegation chief in Iran, said in a statement.

The United States and Israel launched their first wave of attacks on Iran on February 28, triggering a war that has seen Iran strike targets in multiple countries around the Gulf.

"The Iranian Red Crescent Society immediately mobilised its network of staff and volunteers to respond to communities affected by the hostilities," said Martinez.

"This work on the ground by the IRCS and the IFRC is vital to saving lives -- every moment counts."

The IFRC said that 529 IRCS branches were undertaking emergency response operations across 30 provinces and 197 cities.

More than 2,100 response teams and over 6,500 staff and volunteers have been deployed, it said, while emergency teams have been carrying out search and rescue operations.

The emergency appeal funds will go towards shelter support, providing relief items, health services and maintaining water and sanitation services.

The Geneva-based IFRC has already allocated 1.5 million Swiss francs from its Disaster Response Emergency Fund to support immediate life-saving activities in Iran.

The IFRC, which has more than 17 million volunteers in more than 191 countries, is the world's largest humanitarian network.