By Yuri Kulikov
KIEV (Reuters) - Ukraine needs fresh talks to improve the terms of this week's gas agreement with Russia, a senior aide to President Viktor Yushchenko said on Friday, raising fears of new gas supply disruptions to Europe.
The deal, reached by Ukrainian Prime Minister Yulia Tymoshenko, came as a relief for Europe after a two-week cut off in Russian gas supply but it exposed rifts in Ukraine's leadership.
Tymoshenko would not allow the gas deal to be revised, a senior government official said.
Oleksander Shlapak, Yushchenko's economic aide, said Kiev would call for fresh talks with Moscow to renegotiate the deal on better terms for Ukraine.
"I believe the Ukrainian side must again carefully analyse this agreement ... work out proposals to the Russian side on altering this agreement and begin consultations no later than this summer," Shlapak told a news conference.
He said changing the deal was vital to ensure survival of the Ukrainian economy, heading into its worst recession in a decade due to a deepening global financial crisis.
Speaking in Uzbekistan, Alexei Miller, head of Russian gas giant Gazprom, ruled out any revision of the gas deal negotiated between Tymoshenko and Russian Prime Minister Vladimir Putin.
"Where does this suggestion of revising the contract come from? A Ukrainian satirical newspaper?" Miller told reporters.
Slovakia, one of the countries hit the hardest by the interruption of Russian gas supplies, strongly criticised any suggestion of changing the final agreements.
"I consider attempts by Ukrainian President Yushchenko to block the signed contracts from January 19th to be completely crazy," said Slovak Prime Minister Robert Fico.
In a commentary published in Germany's Die Welt newspaper, Gazprom's deputy chief Alexander Medvedev said reopening talks on the deal would only jeopardise European consumers.
"Any attempt to reopen negotiations would be doomed to failure and only burden millions of European citizens," he wrote.
NABUCCO
The gas row intensified the EU's search for alternative sources of energy and injected fresh impetus into the stalled Nabucco project to supply Central Asian gas to EU customers.
Highlighting Moscow's resolve to defend its interests in Central Asia, Russian President Dmitry Medvedev was in Uzbekistan on Friday to win its support for a rival trans-Russian gas pipeline.
In Kiev, the senior government official was adamant that Tymoshenko would not allow renegotiation of the deal.
"They (agreements) represent the country's interests and were drawn up within the framework of Ukraine's strategic and economic interests," First Deputy Prime Minister Oleksander Turchynov told a news conference.
The gas row created a fresh rift between Ukraine's president and prime minister -- allies in the 2004 "Orange Revolution that swept pro-Western politicians to power but at odds on virtually all issues since Tymoshenko became premier again in late 2007.
Tymoshenko says the deal provides the best possible conditions for Ukraine -- a 20 percent discount on European prices and the elimination of intermediaries in the gas trade.
But Yushchenko called it a "defeat," citing steep price increases in the first quarter with no rise in transit fees for Ukraine to offset them.
As Europe, which relies on Russia for a quarter of it gas needs, rushed to find alternative energy sources, Bulgaria announced it would start talks with the EU Commission on the possible restart of a Soviet-era nuclear plant.
(Additional reporting by Denis Dyomkin in Tashkent, Peter Laca in Bratislava, Noah Barkin in Berlin; Writing by Maria Golovnina; Editing by Richard Balmforth)
