Soldiers delivered aid to flood-stricken residents as water levels continued to rise in southern Thailand, where more than 100 people have died in the deluge.

The Thai army deployed helicopters with packed meals, drinking water, and fresh oxygen tanks to a hospital in Hat Yai, Songkhla province, today.

Officials from relevant agencies also visited swamped neighbourhoods, delivering emergency supplies to stranded families.

Lieutenant General Narathip Poynok, commander of the 4th Army Region, said he has ordered helicopters to survey transportation routes and drop food and drinking water to residents.

Songkhla Governor Ratthasart Chidchoo on Monday declared all 16 districts disaster zones and ordered the immediate evacuation of children, the elderly and the sick.

On Sunday, high-clearance trucks arrived to evacuate more than 400 tourists from flooded hotels across the city.

Soldiers, volunteers, and local government units have also been mobilised to hasten relief efforts, but they were hobbled by limited phone signal in the area.

The Disaster Prevention and Mitigation Department said that floods hit nine southern provinces, affecting some 1,128,284 households and 3,221,958 people.

Authorities said today that at least 100 people have been killed in the catastrophic floods, described by Prime Minister Anutin Charnvirakul as 'the worst flooding in 15 years'.

Soldiers, volunteers, and local government units have also been mobilised to hasten relief efforts, but they were hobbled by limited phone signal in the area.

The Thai navy said it was preparing to deploy 14 boats and the aircraft carrier Chakri Naruebet to southern Thailand, with medical teams, supplies, and field kitchens able to supply 3,000 meals a day.

The navy said in a statement: 'The fleet is ready to deliver forces and carry out actions as the Royal Navy orders.'

The Southern Eastern Meteorological Centre said a strong monsoon trough was causing the heavy rainfall, which was expected to ease this week.

Thailand and neighbouring countries in Southeast Asia are in their annual monsoon rainy season which sees soaring temperatures followed by powerful rainstorms in the afternoon leading to widespread flash floods.