By Daniel Wallis

NAIROBI, July 24 (Reuters) - Ethiopia's government is not blocking aid to a remote eastern region, but trade restrictions combined with floods could still trigger a humanitarian crisis there, the U.N. World Food Programme said on Tuesday.

A rebel group in the desolate area bordering Somalia demanded a U.N. investigation after The New York Times quoted Western diplomats and aid officials on Sunday accusing Ethiopian authorities of stopping food aid reaching the Ogaden region.

A WFP spokesman in Nairobi said the government was not "blockading" Ogaden because WFP was distributing food in three of the region's zones, while assessments had started or were about to start in its other three zones.

But it and other donors remained concerned, he said.

Restrictions on trade and the movement of aid due to military operations, as well as seasonal floods, rising prices and other factors could cause a humanitarian crisis among some communities, the WFP's Peter Smerdon told Reuters.

"The military operations and restrictions on movement in some areas have affected all humanitarian actors providing assistance ... including other U.N. agencies and NGOs, but we are working with the government to gain access," Smerdon said.

Ethiopian government officials have not been available to comment on the newspaper article or the rebels' claims.

FLOODS FORECAST

Ogaden is a parched landscape with few roads that is populated largely by nomadic camel herders and is effectively off-limits to most human rights workers and journalists.

Last month, Prime Minister Meles Zenawi announced a crackdown on the Ogaden National Liberation Front (ONLF) guerrillas, who say they are fighting for autonomy for their homeland -- the poorest part of the country. Addis Ababa says the ONLF is a terrorist group bankrolled by arch-foe Eritrea.

WFP said military operations that started in May, then intensified in June, had delayed the dispatch of emergency aid.

But it said 2,200 tons of food had now been sent to three Ogaden zones -- Shinile, Afder and Liben -- where WFP monitors on the ground were checking that it reached people in need.

The U.N. relief body OCHA will also lead an inter-agency team to the region on Wednesday, Smerdon said, where it will meet the local authorities and others.

Any further delays would have serious humanitarian implications, WFP says, as the region suffered a major drought and floods last year and has only just started to recover. More floods are likely in August and September.

Until distributions began again this month, the area's most hungry had received no food aid since January. The situation is worsened by trade restrictions that have pushed up local prices.

"In some cases markets have no stocks at all," Smerdon said.

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