Dmitry Sukhoparov, Russia's national coordinator in the High-Level Group on the CES, told a RIA Novosti news conference: "The CES can work even without Ukraine. We [Russia, Belarus, Kazakhstan] can work when there are three of us."
However, Sukhoparov stressed, "It should not be forgotten that Ukraine means almost 50 million people, and the bigger the market in terms of area, number, GDP and capital, the more efficient the organization we are building will be."
He added: "Therefore, we are interested in Ukraine."
The expert said Belarus, Russia, Ukraine and Kazakhstan produced 95% of the Commonwealth of Independent States' aggregate gross domestic product.
Ukraine would lose some advantages if it refused to take part in the CES, Sukhoparov said. "If a country participates at the stage of developing the agreements, it can still correct something or introduce something of its own," he said. "But when three countries have adopted documents, a new participant will have to join the prepared agreement."
Sukhoparov said experts from the four states were constantly working to consider and coordinate CES documents. "The 93-document package on the establishment of the common economic space will be coordinated in full by August 1," Sukhoparov said.
"Now, we have considered 68 of the 93 documents, out of which 50 have been coordinated by all the four sides," the official said. "There are differences over the remaining documents."
Sukhoparov said the CES's future would be decided at a four-party summit of the High-Level Group, which would be held after August 1.