Vladimir Putin delivered an annual address ahead of planned pro-Navalny protests.
The 44-year-old announced last month he was going to begin refusing food in a bid to get proper medical treatment.
The Russian president, who has been in power for longer than any other Kremlin leader since Josef Stalin, could hold on to his job until 2036.
Russian police arrested around 200 opposition politicians and municipal deputies at a Moscow conference.
"The money hasn't been thrown to the wind," Lukashenko told Putin amid reports he had come to Russia seeking another loan for Belarus.
Russian power giant Nornickel had its compensation appeal rejected and will now pay for the 21,000 tonne spill.