MINSK: President Alexander Lukashenko said Saturday that his Russian counterpart Vladimir Putin has offered full assistance to ensure security in Belarus as thousands held peaceful protests against his rule.

"To talk about the military element, we have an agreement with Russia as part of the union state and the Collective Security Treaty Organization (CSTO).

Such situations fall under that agreement," Lukashenko told defence chiefs, quoted by Belta state news agency.

"I had a long, substantial conversation today with the Russian president... We agreed that at our very first request, comprehensive help will be given to ensure the security of Belarus."

Belarus and Russia have formed a "union state" linking their economies and militaries, while the CSTO is a military alliance between six ex-Soviet states. Lukashenko had a phone conversation with Putin earlier Saturday and the Kremlin said the leaders "expressed confidence that all the problems that have arisen will be resolved soon".

Russia has been the only neighbour of Belarus to back Lukashenko during the mass protests that have gained growing support from Belarusians and drawn international condemnation of police violence and vote-rigging.