Belarus' electoral commission has registered President Alexander Lukashenko and three opponents, including opposition leader Alexander Milinkevich, to stand in next month's presidential election.

Lukashenko, who has since 1994 headed this ex-Soviet republic which the United States has called the "last dictatorship in Europe," is widely seen as the favourite in the vote on March 19.

Critics however accuse his leadership of harrassing the opposition, limiting the opposition's access to the media and packing the electoral apparatus with his supporters.

"I want the election campaign to proceed in strict accordance with the law, unlike in other corners of the planet," the president said on Friday as each candidate was given a chance to speak at the election commission headquarters.

"I warn you that only the Belarussian people will elect the head of state, without pressure from outside," said Lukashenko, who is accused by rights campaigners and the West of clamping down on free speech and political opposition.

Milinkevich, who leads a coalition of opposition parties, slammed current political conditions in the Belarus, a country of 10 million people that lies between Poland to the west, Russia to the east and Ukraine to the south.