Botham said he would walk nearly 375 miles (600 kilometres) from the former war zone in the island's north to the southern home constituency of President Mahinda Rajapakse starting November 1. "It is the daftest thing I have agreed to do... it is going to be in temperatures of 40 degrees (Celsius, 104 Fahrenheit)," Botham told reporters in Colombo while announcing his fund-raising walk. "This is going to be the hardest walk. We have done 1,000-mile walks... walks in the Alps, but nothing like this... We will have a lot of rehydrating to do in the evenings."

Botham advised those planning to join him to bring "a lot of water, you will need it" when walking in the hot and humid conditions of tropical Sri Lanka.

He said it will be the first of "Beefy's Big Walks" to be held outside Britain and was intended to raise money for disadvantaged children in Sri Lanka and around the world.

The Sri Lanka event will be his 15th charity walk since 1985 and he has so far raised over 13 million pounds ($20.1 million).

Proceeds from the Sri Lanka walk will go to the Laureus Sport for Good Foundation, which funds charitable activities in 34 countries.

Botham was expected to be joined on the walk by other cricketing greats -- Brian Lara of West Indies and India's Saurav Ganguly and Kapil Dev.

Botham said getting personally involved with highly publicised walks would help extract more cash from potential donors. "It is good to make appeals on television, but when they see you actually doing something, then they are likely to give more," he said.

The walk is due to end on November 8 at the southern town of Hambantota.

Botham visited Sri Lanka soon after the December 2004 Asian tsunami, which killed more than 31,000 people 0n the island and devastated much of its coastline.

In March 2011 he visited Sri Lanka's northern region nearly two years after the end of a decades-old Tamil separatist war. (AFP)