"Russia wants to destabilise the Transnistrian region and hints Moldova should wait for 'guests,'" Mykhaylo Podolyak, a Ukraine presidential aide wrote on Twitter.

The breakaway region saw explosions hit its security ministry on Monday and a radio tower on Tuesday morning, incidents that follow bellicose statements from Russian officials on Moldova.

"Bad news: if Ukraine falls tomorrow Russian troops will be at Chisinau's gates," Podolyak said, referring to the capital of Moldova, which neighbours Ukraine.

"Good news: Ukraine will definitely ensure strategic security of the region. But we need to work as a team," Podolyak added.

Ukraine's defence ministry said in a statement that Russian troops stationed in the separatist region are on high alert following the explosions.

Kyiv's military intelligence in a statement on social media accused Moscow of preparing a missile strike on Transnistria that would lead to civilian casualties, with the intention of blaming Ukraine.

Transnistria is an unrecognised breakaway region that seceded in 1990, followed by a short war in 1992, with the Russian army fighting alongside separatists against Moldovan forces.