HYDERABAD, India - Rescue workers with boats and helicopters struggled on Tuesday to deliver rations to about 5 million victims of flooding triggered by torrential rains in southern India.

The floods in Karnataka and Andhra Pradesh, described by officials as the world in decades in the region, have killed more than 250 people and left some 2.5 million people homeless. They come soon after large parts of the country suffered a drought.

Millions of acres of farmland went under water, raising fears of a fall in sugar output in Karnataka, the country's third-biggest producer.

While rains have subsided, fears grew that the corn output could also be hit by at least one million tons in the two states, which account for about 35 percent of India's total corn production.

With water levels receding at most places, the focus shifted to relief operations. While rescue workers struggled to deliver food and water rations at many places, some victims complained about the slow pace of relief efforts.

We have no facilities here. Even food and water is not being provided, said a woman at a camp in Kurnool district in Andhra Pradesh, where people staged a protest during a minister's visit.

Officials said extensive damage to roads made the task of delivering relief supplies difficult.

Everybody should understand that we are facing the worst floods of our times, said Mukesh Kumar Meena, a local official.

Fears were also growing about damage to the standing sugarcane crop in western Maharashtra state, the country's biggest sugar producer.

If the rains persist, then there could be damage to the standing crop, said Ajit Chowgule, secretary of the Maharashtra State Cooperative Sugar Factories Federation Ltd.

In neighboring Karnataka, where about two-thirds of the 54 sugar mills have delayed crushing by a week to 10 days, at least 250,000 hectares of farmland have been destroyed.

In Andhra Pradesh, the Krishna river breached its embankment at a few places, inundating dozens of villages and forcing local authorities to evacuate people with boats. Some 200,000 people in more than 200 villages have been moved to higher ground.

The rising water level continues to pose a threat to several villages and Vijayawada, a city of about a million people.

Wherever the embankments are weakening or there are reports of minor breaches, we are using sandbags to strengthen them, said district official Piyush Kumar.

The biggest challenges are gaining access to marooned villages and providing clean drinking water to check the spread of water-borne diseases, said the head of the International Committee of the Red Cross in India.

The magnitude of the disaster is enormous, so the relief and rehabilitation effort is a massive operation, said Peter Ophoff.

We have water receding in most areas and no new heavy rains, but the real work will start now.

(Additional reporting by Habib Beary in BANGALORE; Writing by Rina Chandran; Editing by Krittivas Mukherjee and Sugita Katyal)