Russia's pipeline monopoly on Monday denied a cut in oil supplies to the Czech Republic was retaliation for that country's decision to host a US missile-defence system, Interfax news agency reported.

The cut in Russian oil supplies was the result of a decision by two Russian companies to refine more oil at home instead of exporting it, the deputy head of state-owned Russian pipeline monopoly Transneft was quoted as saying.

"This has no relation to politics. It was purely commercial," Mikhail Barkov was quoted as saying by the news agency. He said the shortfall was likely to be made up by another Russian company "before long."

Russian oil supplies fell by between a third and half this month, the Czech foreign ministry said last week, adding that the reason was probably technical.

The cut was announced shortly after Prague agreed to host a US anti-missile radar system that Russia claims is aimed at undermining its nuclear deterrent.

In Prague, the industry ministry said the Russians had told the government that the problems were technical and not political.

"The Russian side said that they had encountered technical problems and assured us that there was nothing political about this," Matyas Vitik, of the Czech industry ministry's press department told AFP in Prague.

The Czech Republic should get an indication of how soon supplies will be restored when delivery schedules for August are published on Tuesday, industry ministry spokesman Tomas Bartovsky told AFP.

So far, oil deliveries from Russia are 15 percent down on their normal level since the start of the month, he added.

The Czech Republic relies on the Druzhba pipeline for most of its oil but can also be supplied via the Ingoldstadt pipeline which runs through Germany. The country has around three months supplies of oil in stock.