Morgan Tsvangirai said he fears that hunger and frustration, along with the continued dismantling of services such as schools and hospitals, could fuel unrest or violence if a legitimate government does not step in.
"The possibility of chaos and the spontaneous reaction because people have nothing is very, very high every day that passes without this agreement being implemented," Tsvangirai told The Associated Press during a visit to Berlin.
Zimbabwe’s economic meltdown has led to chronic shortages of food, gasoline and most basic goods; daily outages of power and water; and the collapse of health and education services.
The country is also in political deadlock, with a power-sharing deal signed Sept. 15 between Mugabe’s party and Tsvangirai’s Movement for Democratic Change having stalled over the allocation of ministries.
Tsvangirai came first in a field of four in a first round of presidential voting in March, but did not avoid a runoff against second-place finisher Mugabe, who has been in power since independence from Britain in 1980.
Tsvangirai withdrew from the June 27 runoff because of attacks on his supporters. Mugabe went ahead with the vote, which was denounced as a sham by observers at home and abroad.
This week, Tsvangirai visited Berlin and Paris to ask European governments for aid as food supplies in Zimbabwe run short. The opposition party estimates that 5.5 million people there could be reliant on food aid by January.
German Deputy Foreign Minister Reinhard Silberberg met with Tsvangirai Thursday and pledged euro500,000 ($625,000) to Zimbabwe.
French Foreign Minister Bernard Kouchner pledged support in Paris on Tuesday but no new commitments on aid, saying access to the needy in Zimbabwe is a major obstacle for aid groups.
Tsvangirai planned to fly from Germany to South Africa on Friday, though was traveling without a passport because he said Mugabe’s government had refused to renew it.
"This is a manifestation of a lot of bad faith on his part and abuse of power that he legitimately does not have," Tsvangirai said.