Zimbabwe's President Robert Mugabe has resigned, the speaker of the country's Parliament said, bringing an end to his 37 years of rule.

The announcement came as Parliament began proceedings to impeach him, six days after the military seized control in the capital, Harare, and placed the 93-year-old leader under house arrest.

Crowds in the streets of Harare broke out in rapturous celebrations, raising their fists and waving Zimbabweans flags to mark the historic moment.

As Mugabe's letter was read out in Parliament, lawmakers broke out in thunderous applause and cheers/

Mugabe's resignation marks the an end of an era in Zimbabwe. He ruled the country with an iron fist for almost four decades and is the only leader the nation has known since it achieved independence from Britain in 1980.

The leader had clung onto power for the past week, despite repeated calls for him to step down.

Mugabe's political demise is the consequence of a struggle over who would succeed him in the ZANU-PF, a party split between those loyal to the former vice president, Emmerson Mnangagwa, and supporters of Mugabe's wife, Grace Mugabe.

It was a humiliating departure for Mugabe, who clung onto power for a week but eventually buckled to pressure.

The party he co-founded to usher the country into independence ousted him, the military that he commanded placed him under house arrest and his most powerful allies abandoned him.

Mugabe rose to power as a freedom fighter and was once regarded as Zimbabwe's own Nelson Mandela, but he quickly waged a campaign of oppression to shore up his authority, extinguishing the political opposition through violent crackdowns.

Mugabe's hardline policies also pushed the country into poverty. Its flourishing economy began to disintegrate after a program of land seizures from white farmers, and agricultural output plummeted and inflation soared.

Over the decades, Mugabe and his wife face fierce criticism for leading lavish lifestyles as the country was plunged into economic ruin.