Vietnam could miss its 2013 rice export target of 8 million tonnes due to growing instances of cancellation of export contracts that had already affected shipments of nearly 1 million tonnes so far this year, state media and traders said.

The cancellations came due to a slide in global rice prices and import restrictions in the Philippines, one of the world's top buyers of the grain, the Vietnam Economic Times newspaper quoted the Vietnam Food Association, the industry body, as saying.

A growing volume of deal cancellations would mean higher stocks of rice in Vietnam, pressuring its export prices further. Competing rice exporting nations such as Cambodia, Myanmar and Pakistan also stand to benefit from Vietnam's falling sales.

Vietnam, the world's second-biggest rice exporter after India, had contracted to ship 6.8 million tonnes so far in 2013, of which 938,000 tonnes had been cancelled, the newspaper cited the association's data as showing.

"Most of the cancelled contracts were for China's market," Chairman Truong Thanh Phong of the food association was quoted as saying. He said Chinese buyers cancelled the deals following falls in global prices.

Phong could not be reached for comments.

Benchmark Thai 5 percent broken rice was quoted at $470 a tonne at the end of July, down 17 percent from end-2012, while the Vietnamese variety with 5 percent broken grain lost 7 percent over the same period. The Vietnamese grain hit its 2013 low of $360 a tonne on June 19.

Vietnamese exporters cancelled some contracts signed at low prices and compensated buyers, while several Philippine buyers also had to abort their import deals as they failed to secure import quotas, the newspaper said.

The Philippines' grains agency increased its rice stocks by about 14 percent in the first half of 2013, buying aggressively from farmers to keep prices stable and avoid further imports if crops are damaged in the typhoon season.

"The total volume of rice contracts is often far above actual shipments because exporters, having anticipated prices may rise, would register their contracts before the deals are signed," said a trader with a foreign firm in Ho Chi Minh City.

But when prices do not rise as expected, exporters cancel the registered deals, the trader said.

Exporters need to register rice contracts with the Vietnam Food Association to ensure good export pricing and in order to secure loading permission. The association sets a floor price and checks to see if any exporters violate the rule by selling below that floor.

"It is unlikely that Vietnam will achieve its rice export target this year, as traditional importers have reduced their purchase and there is also more competition from Myanmar, Cambodia and Pakistan," the trader in Ho Chi Minh City said.

Vietnam has targeted exports of around 8 million tonnes of rice this year, on par with shipments in 2012.

Rice exports at the end of July had fallen nearly 11 percent from the same period last year to 4.23 million tonnes, Vietnam Customs data show.