MOSCOW, April 4 (Reuters) - Belarus' President Alexander Lukashenko will travel to Moscow on Wednesday for two days of talks with Russian President Vladimir Putin, the Kremlin said.

Kremlin spokesman Dmitry Peskov said last week the two leaders would discuss Lukashenko's call for an immediate ceasefire in Ukraine at an upcoming face-to-face meeting.

Putin and Lukashenko will hold talks on "topical bilateral and international issues" on April 5, before a meeting of the Supreme Council of the Union State on April 6, the Kremlin said in an announcement published on Tuesday.

Russia and Belarus are formally part of a Union State, a borderless union and alliance between the two ex-Soviet countries, though long-standing plans for closer integration of their economies have repeatedly stalled.

Moscow is Belarus' key political and financial backer, while Lukashenko allowed Putin to use Belarus' territory as a launchpad for Russia's invasion of Ukraine last year.

Last month Putin said Russia would deploy tactical nuclear weapons to Belarus.

Defence Minister Sergei Shoigu said on Tuesday that Russia was boosting Belarus' nuclear capabilities in response to Finland joining the NATO military alliance.