Belarus Foreign Minister Mikhail Khvostov last week dismissed recent suggestions by Moscow that the former Soviet republic should become part of Russia.
"For the first time we definitely told Russia's new leaders that Belarus will not be integrated into Russia, in whole or in part," Khvostov said in comments televised on Belarus's state-owned channel.
"I think that both Russia and we understand that a union must be made up of two sovereign subjects of international law, and we are ready to be part of such a union," he added.
Khvostov's comments echoed Belarus President Alexander Lukashenko's angry rejection of the terms posed by Russian President Vladimir Putin for building a new union between the two neighboring former Soviet republics.
Raising the stakes following five years of unproductive negotiations over possible union, Putin earlier this month suggested to Lukashenko that he integrate his republic into Russia and adopt the Russian constitution.
The only alternative, said Putin, would be a loose alliance based on the European Union, in which Russia and Belarus each preserved full independence.
"Two states will never create something like the European Union, and we should not deceive ourselves on this score. We have already determined what our key terms are and put them into our 1999 accord," Khvostov said.
"We should not step away from that accord, it would not benefit either Russia or Belarus," he added.
Putin's proposal came with relations between Moscow and Minsk at an all-time low over an economic and political union treaty signed in 1999 which, despite repeated efforts, has failed to lead to any meaningful political or economic alliance.
The proposed union would create a mechanism by which the two countries could devise joint foreign and economic policies while preserving each state's full sovereignty.
Many Russians suspect that Lukashenko would like a closer union with Russia to rescue Belarus from its economic downfall and fear the authoritarian leader and his unpredictable outbursts.
Opinion polls show that at least half of the Belarus population want their country to retain its sovereignty.