MANILA, Philippines -- The Philippines scrapped its largest rice tender of the year Monday and said it preferred to hold back importing until prices fall, sending a signal to world grain markets that rice prices might have peaked.

Manila's willingness to wait could give some breathing space to importers scrambling for cargoes in recent weeks. Prices have trebled this year with world stocks at record lows and strong demand.

Leaders attending the annual meeting of the Asian Development Bank (ADB) in Madrid warned Sunday the region was at risk of undoing a decade of gains because of soaring food prices that could also spark social unrest.

"We feel that we are not pressured to buy now," said Ludovico Jarina, deputy administrator of Manila's National Food Authority, (NFA), the state's grain importing arm.

The Philippines, the world's top rice importer, said prices were on a downward trend and, after cancelling a tender for 675,000 tons of the grain, said it could wait until later this year, possibly the third quarter, to return to the market.

Jarina officially declared Monday's eagerly-awaited tender a failure after Vietnam's state-owned Vinafood II, the sole participant, failed to supply a bank guarantee.