* Raw sugar ample, price fall outstrips decline for whites

* Cevital, Al Khaleej refiners upped raw buying in March

* Mexican sugar could be delivered against Liffe Aug expiry

By David Brough

LONDON, April 24 (Reuters) - A strong whites-over-raws sugar premium is boosting incentives for refiners to process and export refined sugar, while low prices are encouraging brisk global demand.

The August/July whites-over-raws premium, a measure of refining profitability, rose to around $115 per tonne on Wednesday from $107 a month ago.

Whites premiums above $90 a tonne are generally considered to be profitable for refining.

"Refiners' activity has been quite strong," said Toby Cohen, a director of London-based commodities house Czarnikow.

"There is a fundamental backdrop of good white sugar demand, and that is expressing itself through the premium."

Ample availability of raw sugar due to strong harvests and a global surplus pushed raw prices to their lowest level in more than 2-1/2 years earlier this month. Benchmark raw sugar futures

SBc1 have dropped by around 9 percent so far this year.

Tighter supplies, meanwhile, have helped prop up white sugar prices by comparison. Benchmark white sugar futures LSUc1 have fallen by a smaller 3.2 percent this year, and since mid-February have risen in price.

Although performing better than raw sugar, refined sugar prices are still low enough to attract strong demand, particularly from North Africa and East Africa.

In the Middle East, white sugar shipments have already begun ahead of Ramadan, the Muslim month of fasting, which starts this year on July 9 and is followed by three days of celebration after it ends on Aug. 7.

Algeria's Cevital sugar refinery and Dubai's Al Khaleej refinery, one of the biggest in the world, both boosted raw sugar buying in March from previous months, dealers said.

Cohen said he expected brisk demand worldwide to help keep the white sugar premium firm for the remainder of this year.

IMPORTS TO REFINERIES

One London-based analyst estimated that the world's leading sugar refineries imported around 1 million tonnes more raw sugar than initially expected in the first quarter of this year.

Competition to sell whites is stepping up as Middle East, Indian, Pakistani and Thai refiners increase processing and look to export.

In the Americas, Mexico's sugar refiners are expected to export substantial supplies from a huge surplus in the coming months.

For the first time in more than 20 years, Mexican sugar earlier this month was delivered against expiry of the Liffe May white sugar futures contract.

Dealers forecast that 500,000 to 800,000 tonnes of Mexican raw and white sugar, mainly whites, would enter the international market by September.

They said some of the surplus could be delivered against the July 16 expiry of the Liffe August white sugar futures contract

LSUc1 .

(Editing by Jane Baird)

((David.Brough@thomsonreuters.com)(00442075428064)(Reuters Messaging: david.brough.thomsonreuters.com@reuters.net))

Keywords: SUGAR REFINING/