MANILA, April 18 (Reuters) - Vietnamese trading firms are expected to feature prominently at the Philippines' May 5 tender for half a million tonnes of rice after taking a backseat at a similar tender this week, officials and traders said on Friday. 

 "I think they will participate next month, otherwise they would have given us the volume yesterday," said Conrad Ibanez, assistant administrator at the National Food Authority, the grain-importing arm of the state. 

  "Probably they are reserving that for the May 5 tender." 

  The Philippines, the world's biggest rice importer, attracted less than two-thirds of the 500,000 tonnes it had requested in Thursday's tender and the bulk, or 195,000 tonnes, came from Thailand. 

Prices at the tender were on average over $1,000 a tonne, cost and freight, nearly 50 percent higher than the last rice tender in March, when Manila bought 335,500 tonnes at an average price of $708.04 a tonne.

   Vietnam, the Philippines' biggest rice supplier, offered only 80,000 tonnes of rice of the 25 percent broken variety.

   The tender will be awarded next week.
   Rival trading firms said Vietnamese dealers were waiting to participate in next month's tender, which is restricted to state-owned ompanies and dealers who can attain financial guarantees from their governments.

   Hanoi often regards contracts secured by Vinafood 2, the country's largest rice exporter, as government deals.

   "The conspiracy theory is that the Vietnamese are holding back till next month. It's bad for the Philippines but good for them. I can't blame them, I would do the same," said a Manila-based dealer, who declined to be named.

   But a Vietnam Food Association official said three Vietnamese firms had only sought to sell 80,000 tonnes at the Thursday tender because of a government ban on new export deals aimed at controlling inflation.

   He said, without elaborating, that Vietnam was interested in the May tender.
   The Philippines is scrambling to secure enough rice supplies to cover a traditional lean period in the third quarter and Thursday's tender was the third in a row that Manila failed to attract sufficient volume.

   The country is having to pay more at each auction to buy its national staple and then sell it at a large discount to poor consumers. 
   Thai 100 percent B grade white rice, considered the world's benchmark, has tripled in price to $950 per tonne since the start of 2007 and is expected to keep climbing, setting the stage for an even more expensive Philippine auction next month.

   Based on Thursday's tender prices, the price per kilo was around 44 pesos compared with the 18.25 pesos a kilo that subsidised rice is sold at.

   Fears that the government will have to increase the price of subsidised rice has encouraged thousands to queue for hours in the heat to stock up on the grain.

   Manila and Hanoi have already signed an agreement for Vietnamese traders to supply up to 1.5 million tonnes of rice for this year but the Vietnamese government has already said only around 1 million may be possible due to rising food inflation at home.

   Excluding Thursday's tender, Manila has bought between 700,000-800,000 tonnes of rice from Vietnam this year and 1.28 million tonnes in total from a variety of countries, including Thailand, the United States and Pakistan as well as Vietnam.

 (Reporting by Carmel Crimmins; Additional reporting by Ho Binh Minh in Ho Chi Minh City; Editing by Raju Gopalakrishnan and Ben Tan) (( This e-mail address is being protected from spam bots, you need JavaScript enabled to view it ; Reuters Messaging: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it ; + 63 2 841 8934)) Keywords: PHILIPPINES RICE/TENDER