"The first convoys of Russian servicemen from the regional force group have arrived in Belarus," the ministry said, adding that their mission was "exclusively to strengthen the protection and defence of the border".

Images from the ministry showed soldiers welcomed by women wearing traditional costumes and handing out bread and salt.

Last Monday the leader of Belarus Alexander Lukashenko claimed Ukraine was plotting to attack his country and announced a joint force with Moscow.

Lukashenko accused Poland, Lithuania and Ukraine of training Belarusian radicals "to carry out sabotage, terrorist attacks and to organise a military mutiny in the country".

The deployment raised fears that Belarusian troops could join Russian forces in their offensive in Ukraine.

On Friday Lukashenko told Russian journalists the Belarusian army and its 70,000 people would constitute the "base" of this joint force.

The Belarusian leader did not specify how many Russian soldiers were expected to join, but said "we do not need to ask for 10,000-15,000 people from Russia. They have other issues over there, as you know".

Minsk said Tuesday that the contingent was "purely defensive".

Ukrainian President Volodymyr Zelensky accused Russia of "trying to directly draw Belarus into this war" at a G7 meeting last Tuesday.

Zelensky called for an international observers mission to be placed on the Ukraine-Belarus border.

In an interview to NBC released Friday night, Lukashenko said his country supported Russia but "we did not kill anyone and we are not going to kill anyone."

"No one asked us to get involved in this operation, not Russia in this case, and we do not intend to get involved," Lukashenko said.

Lukashenko said his country was "treating Russians and Ukrainians, feeding Russians and Ukrainians" and welcoming Ukrainian refugees.

Lukashenko is an ally of Russian President Vladimir Putin and allowed Belarusian territory to be used by Moscow's troops to launch a military operation against Kyiv in February.

But Belarusian armed forces have up to now not taken part in the offensive.

Belarus relies financially and politically on its key ally Russia.