Belarus investigators have officially charged a protest leader with incitement to undermine national security, the Investigative Committee said in a statement on Wednesday.

Kolesnikova was charged with calling for "actions aimed at undermining Belarusian national security" using the media and the internet, the committee said.

Kolesnikova, 38, is currently in jail in Minsk after ripping up her own passport last week to thwart an attempt to expel her to Ukraine.

A member of an opposition coordination council, she was the last of three female politicians left in Belarus who joined forces before an August 9 presidential election to try to challenge President Alexander Lukashenko.

A vocal critic of Lukashenko, she played an important role in weeks of mass demonstrations and strikes by protesters who accuse Lukashenko of rigging his re-election.

Lukashenko, who has been in power for the last 26 years, denies that allegation and has accused foreign powers of trying to topple him in a revolution. He has responded with a crackdown which some of those detained say includes torture and beatings.

While Europe has said it does not recognise Lukashenko as the legitimate leader of Belarus, Russia has supported its ally. 

On Monday, Russia agreed to a $1.5bn loan with Minsk, President Vladimir Putin said, adding that the Belarusian people should resolve the crisis without foreign interference.

Putin, in comments broadcast on television from talks alongside Lukashenko in Russia's Sochi, said he thought a proposal by the Belarusian strongman to carry out constitutional reform was logical and timely.