UPDATE 1-Emerging Asia faces food price shock-ADB

(Recasts, adds details, ADB comment)

MADRID, April 30 (Reuters) - A billion people are seriously affected by soaring food prices in Asia's developing economies, the fastest-expanding in the world, the Asian Development Bank (ADB) said on Wednesday.

Measures to counter the surge in food and fuel prices will be the focus of the ADB's May 3-6 annual board meeting in Madrid, Spain, the bank's Managing Director Rajat Nag said.

"This is already a grave problem for the poor," Nag told a press conference. "It's an issue of rising prices rather than supply problems."

Higher food prices on global markets have been blamed on rising Asian demand, weaker harvests, biofuels and higher energy costs.

Inflation is expected to rise to a decade high 5.1 percent this year in emerging Asian countries, according to the ADB.

"We believe this is the greatest policy challenge which we face," he said.

The bank is planning loans for food aid programs and long-term projects to improve agricultural infrastructure in Asian countries.

The ADB approved $10.1 billion in low-cost loans in 2007 for projects and technical assistance in poorer countries.