KIEV, Ukraine—Russian President Dmitry Medvedev called Viktor Yanukovych this weekend as soon as the Ukrainian president-elect's challenger dropped a legal battle to block his inauguration. According to the Kremlin, the two men agreed that Mr. Yanukovych would visit Moscow in early March.

On Sunday, however, Mr. Yanukovych's aides declined to confirm or deny anything about a visit, though his Web site posted the Kremlin announcement. Hanna Herman, a legislator and a deputy leader of Mr. Yanukovych's Party of Regions, said...