HARARE (AFP) - Zimbabwe's leaders signed a historic deal Monday that will see President Robert Mugabe share power with his archrival in a bid to resolve a ruinous political crisis in a country in economic meltdown. South African President Thabo Mbeki, who brokered the deal, however said later in the day that the unity government had not yet been finalised, calling on the two parties to do so as soon as possible. Shortly after signing the deal at a ceremony in the Zimbabwean capital, the 84-year-old Mugabe said he was "committed" to working with long-time rival Morgan Tsvangirai in the new government. "Let us be allies," said Mugabe, who has ruled the country since independence from Britain in 1980. "People will want to see if what we promise is indeed what we strive to do. We are committed, I am committed, and let us all be committed." But the veteran leader, who had previously vowed that the opposition would never rule in his lifetime, also showed his defiant side, repeating earlier warnings about outside influence in his country. While his rhetoric had cooled as power-sharing talks pushed ahead in recent weeks, Mugabe has in the past repeatedly labelled Tsvangirai a stooge of Western powers, particularly former colonial ruler Britain. "We must resist those who want to impose their own will on us," Mugabe said. "Zimbabwe is a sovereign country, only the people of Zimbabwe has the fundamental right to govern it. They alone will set up government, they alone will change it." Mugabe will remain president under the deal, while Tsvangirai, who leads the Movement for Democratic Change (MDC), will serve as prime minister. Tsvangirai used his first platform as head of government to call on Zimbabwe's rival parties to work together to unite the country. "I, the Prime Minister of Zimbabwe, call ZANU-PF and MDC to unite Zimbabwe. Divisions belong to the past," Tsvangirai said. He also called for the economically shattered southern African country's doors to be reopened to international aid. Tsvangirai said, "We need to unlock our doors to aid, we need medicine, food, and doctors back in our country. "We need electricity, water, petrol for our vehicles, we need to access our cash from bank." Over the past decade, Zimbabwe's economy has collapsed with the world's highest inflation rate, chronic shortages of foreign currency and food, skyrocketing unemployment and widespread hunger. Mugabe, 84, was greeted with some jeers as he entered the Rainbow Towers Hotel in Harare for the signing. The new government is the result of protracted talks mediated by Mbeki between Mugabe's ZANU-PF and the MDC. While details of the accord reached on Thursday were to be formally unveiled. later Monday, a source close to the talks told AFP that both Mugabe and Tsvangirai would co-lead the economically battered nation. The president is to remain in control of the armed forces, sources have said, while Tsvangirai's powers would include authority over the police and secret services.