Alexander Lukashenko, Europe’s longest-serving leader, has extended his 31-year rule in Belarus after being declared the winner of a presidential election that his exiled opponents and Western countries have denounced as a sham.

As an East African bloc urged an immediate ceasefire in eastern Democratic Republic of Congo, Rwandan-backed M23 rebels who seized the city of Goma extended their advance on Wednesday, and Congo said it planned a campaign to recover lost territory.

Alexander Lukashenko, who has ruled the ex-Soviet state for 31 years, held a four-hour press conference musing that some of his opponents "chose prison", after winning 88 per cent of the vote.