Foreign Secretary Liz Truss said the prison sentence was "another appalling attempt by Myanmar's military regime to stifle opposition and suppress freedom and democracy".

"The United Kingdom calls on the regime to release political prisoners, engage in dialogue and allow a return to democracy. The arbitrary detention of elected politicians only risks further unrest," she added.

The 76-year-old Suu Kyi has been detained since the generals ousted her government in the early hours of February 1, ending Myanmar's brief democratic interlude that followed her release from previous lengthy house arrest in 2010.

The junta has since added a slew of other indictments, including violating the official secrets act, corruption and electoral fraud. The Nobel laureate faces decades in jail if convicted on all counts.

Former president Win Myint was also jailed on Monday for four years under the same initial charges of incitement and Covid-19, with a junta spokesman telling AFP that the pair would not yet be taken to prison.

The sentences have been greeted with a chorus of condemnation from rights groups and Western governments.

Britain's former prime minister Tony Blair added to the criticism, saying their "imprisonment on trumped up charges shows the ruthless brutality of the current regime in Myanmar and their intention to completely destroy the country's fledgling democracy".

"What is happening day by day in the country is tragic, cruel and completely without justification," he added.

"The junta must understand from the reaction of the world's leading nations, that there is no way back into the international community without setting out a clear and credible plan for the restoration of civilian rule."