Brussels  - Russia was wrong to cut off all gas supplies to and through Ukraine regardless of who was in the right over the two countries' gas dispute, a top United States official said Wednesday.

"We want to have good relations with Russia, but they should be based on 21st-century principles, not principles of spheres of influence ... Is there no better way to handle a commercial dispute than cutting off gas and affecting third parties?" US Assistant Secretary of State for Europe Daniel Fried said in Brussels.

"I'm not taking Ukraine's side in the actual debate about pricing, and I don't think we should ... Turning off all of the gas in a way that impacts on downstream consumers raises questions about Russia's reliability as a supplier," he said.

He questioned whether the row between Moscow and Kiev over gas prices and contracts could still be seen as a purely commercial one after Russian President Vladimir Putin approved the closure of all gas deliveries to Ukraine in a television broadcast.

"To have the prime minister on television ... signals that this is a political issue suddenly, and not simply a commercial dispute," he said.

But he also called on both Ukraine and Russia to be more transparent in their management of the gas trade, describing the gas- transit business in the region as "notoriously opaque" and insisting that Ukraine should pay market prices for gas in the long term.

And he urged European states to put more effort into diversifying their energy supplies, saying that Europe had not yet drawn all the necessary lessons from the last major Russia-Ukraine gas row in 2006.

"I don't think there's been quite enough" progress on diversification since the 2006 crisis, he said, stressing the need for European states to develop a system for sharing gas supplies in times of shortage.

"Europeans should ask whether the current efforts are adequate. .. We hope that Europe will develop energy policies which will have an element of solidarity in them," he said. (dpa)