|Belarus security agents arrested about 600 people who were demonstrating outside a Minsk jail on Sunday [AFP]
A group of leading opposition activists in Belarus have been charged by the country's security agency KGB in the wake of post-election violence and mass arrests.
Human-rights groups in the country said seven of the nine presidential candidates faced up to 15 years in jail.
Some were beaten in the course of being arrested and a lawyer for one of the candidates said his client is unable to walk due to his injuries.
Ales Belyatsky of the human-rights centre, Vesna, said on Wednesday the seven opposition candidates were charged for organising mass disturbances.
The former Soviet state's security agency, KGB, filed the charges following the arrest of some 600 people, including the candidates, who were demonstrating outside a Minsk jail over the weekend.
Sunday's election gave Alexander Lukashenko a fourth term in office with 80 per cent of the vote.
Al Jazeera's Neave Barker reporting from Minsk said more than 400 protesters have already been sentenced to between five and 15 days in jail.
"But there could be much stiffer sentences for 18 other people including seven former opposition presidential candidates," he said.
"The arrests have sparked outcry from opposition groups, human-rights organisations and international observers in the country who have described the Belarus election as deeply flawed."
Grigory Kostusyev and Dmitry Uss, two of the candidates charged, were released but later summoned to KGB offices for further questioning on Wednesday.
Other candidates charged include Andrei Sannikov, who the Central Elections Commission's widely disputed count says was the top vote getter among the challengers.
Kostusyev told the Associated Press in a brief telephone interview that "the regime has shown its true essence" and that "we've been thrown 10 years into the past".
Sannikov's wife Irina Khalip and Nataliya Radina, the editor of an opposition website affiliated with Sannikov, also face the charges, according to Vesna.
Vladimir Neklyayev, another prominent challenger, was beaten as he tried to lead a column of supporters to the protest in central Minsk on Sunday night.
He was hospitalised, but later forcefully taken from the hospital and placed in KGB custody.
Pavel Sapelko, Sannikov's lawyer, said his client was beaten severely during arrest, received blows to his head and is now unable to walk due to a suspected broken leg. He has asked for the injury to be X-rayed, but has been refused.
"He feels very bad and looks very bad," Sapelko told the Associated Press.
Tamara Sidorenko, a lawyer, said her client Neklyayev was beaten as he tried to lead a column of supporters to the protest in central Minsk on Sunday night. He was hospitalised, but later forcefully taken from the hospital and placed in KGB custody. Sidorenko said she has not been allowed to visit him.
The other arrested candidates are Nikolai Statkevich, Vitaly Rymashevsky and Ales Mikhalevich.
Belarus' economy during Lukashenko's rule was propped up by energy subsidies from chief ally Russia.
The country serves as a buffer between Russia and NATO, and as a transit route for Russian gas channelled to Europe.
But relations with Moscow have been on the rocks in recent years, and Lukashenko, a former state farm director, has been courting the West.
Lukashenko crushed dissent harshly in the early years of his rule, jailing opponents and muzzling the media.