Teryokhin said the four economies were too different to function smoothly in a single economic bloc. Ukraine, he said, would develop bilateral economic relations with each of the countries instead.
Yesterday, however, President Viktor Yushchenko appeared to take an opposing view.
He said Ukraine will participate in the SES, and is bringing a series of proposals to a planned 26-27 August meeting designed to review the prospects of the Russian-led grouping.
The SES was formed in 2003, but has yet to begin functioning. It is seen by some as an attempt by Moscow to restore its dominance in the region.
Yushchenko, perhaps striving for balance, said Kyiv is eager to maintain warm ties with both the East and the West.
"Keeping in mind that both directions are crucial for us, it is important to understand our priority -- we cannot accept circumstances under which the organization of our eastern policy would block or come into conflict with the principles of our policy toward the European Union," Yushchenko said.
Oleksiy Kolomiyats, head of the Kyiv-based Center for European and Transatlantic Studies, said the SES confusion points to a wider lack of consistency in Ukraine's foreign policy that could ultimately damage the standing of the administration.
"On the whole, it indicates that there are different attitudes, all of which are voiced publicly," Kolomiyats said. "There are several aspects to this. To begin with, there are several visions of projects like the Single Economic Space, and also of some other [projects]. On the other hand, it indicates that top-level officials in the current Ukrainian administration are not coordinating their positions."
Kolomiyats said that Yushchenko opposed the SES while he was still a member of the political opposition before the Orange Revolution catapulted him to the presidency.
Now, according to the analyst, Yushchenko at times resembles the politicians of the ousted regime, who favored close ties with Russia.
Nikolai Petrov of the Moscow Carnegie Center told RFE/RL that Ukraine's new government has become notorious for voicing contradictory opinions on key policy issues.
"There were very serious disputes over reprivatization -- reversing all those deals made while [former President Leonid] Kuchma was in power," Petrov said. "Yushchenko and [Prime Minister Yuliya] Tymoshenko had very different attitudes on the issue. They were publicly in conflict."
Petrov said the disparate opinions are the result of a ruling coalition that is composed of politicians ranging from liberals to socialists.
But he said the government remains effective and unified, at least, in its pro-European stance. But he said even this solidarity may suffer ahead of next spring's parliamentary elections, when candidates may put voters' concerns above those of the government.
"I think that the government has some kind of policy. Opinions may differ on its value, but it is more or less effective," Petrov said. "But the other problem is that in the future, at least up until the elections, this efficiency will decrease, not increase."
For the meantime, Yushchenko is trying to unite his administration behind a more coherent policy and prevent contradictory statements from reaching the public.
Ukrainian Foreign Minister Borys Tarasyuk announced yesterday that Yushchenko had signed a decree that would bring an end to public government misstatements.
From now on, Tarasyuk said, only three officials will have the right to voice the country's official policies regarding foreign issues.
"The official position and official statements about the state's foreign policy can be presented only by three officials -- the president, the prime minister, and the foreign minister," Tarasyuk said.
Observers said that Tarasyuk's announcement is a swift reaction to the embarrassment sparked by the SES controversy.
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