BUDAPEST, July 26 (Reuters) - Hungary will face fuel

shortages from September if full Russian oil flows are not

restored, a government official said on Friday, accusing Ukraine

of blackmailing it by partially suspending supplies.

Eastern European Union members Slovakia and Hungary have

been hit by a stop in flows from Russian group Lukoil

coming via Ukraine after sanctions were imposed on the company.

This has put pressure on Hungarian and Slovak refineries,

all owned by Hungary's oil and gas group MOL.

It is also angering governments in Bratislava and Budapest

which, in the Russia-Ukraine war, oppose sanctions against

Moscow and sending military aid to Kyiv. They are seeking EU

mediation in the dispute.

Gergely Gulyas, chief of staff for Hungarian Prime Minister

Viktor Orban, on Friday said Ukraine's decision was blackmail

for their positions on Russia's war in Ukraine.

"If the situation is not resolved, there will be a fuel

shortage ... a solution must be found by September," Gulyas told

a news conference. "Ukraine is blackmailing the two countries

that are standing for peace and ceasefire."

Oil deliveries from other Russian suppliers have not been

interrupted.

Ukrainian presidential aide Mykhailo Podolyak rejected

Budapest's accusations, saying that Ukraine's decision to

suspend Russian oil transit to Hungary and Slovakia had nothing

to do with blackmail.

In the Lukoil dispute, the two countries want the European

Commission to use an association agreement with Ukraine, based

on which they said Kyiv could not block oil transit.

Slovakia called on the Commission on Thursday not to delay,

saying it was hostage to the EU and Ukraine and asking whether

citizens needed to queue for petrol or face rising prices first.

Hungary's EU Affairs Minister Janos Boka said that Hungary

was examining whether Ukraine's actions breached World Trade

Organisation regulations.

Gulyas said Budapest was looking for solutions.

"One is that the Ukrainians admit that they cannot do this

to two EU countries," he said. "Another is that the European

Commission helps us, and the third is that we find a legal

loophole that allows the oil to be transferred by someone not

affected by the sanctions."

The Ukrainian energy ministry did not immediately respond to

a request for comment.

MOL also did not immediately reply to questions.

Tamas Pletser, an oil and gas analyst at Erste Group Bank in

Budapest, said big fuel shortages were not likely after the

summer months but replacing Lukoil supplies would be difficult

for MOL.

"Lukoil can be replaced by MOL if they want to; it wouldn't

be simple but it's possible," he said. "Lukoil's size makes it a

good choice to sanction, it's not irreplaceable but still

painful to lose."

The EU imposed sanctions on Russian oil in 2022 although

Slovakia, Hungary and the Czech Republic gained exemptions due

to their reliance.

On Wednesday Fitch Ratings said refineries in Slovakia and

Hungary faced significant credit risk after the Lukoil

sanctions.

Czech refineries, owned by Poland's Orlen ( PSKOF ), do not

have Lukoil as a supplier, so have not been directly impacted by

the dispute.