HARARE (AFP) - Zimbabwe's President Robert Mugabe swore in his two vice presidents Monday, a senior official said, casting doubt on a new mediation effort aimed at saving a power-sharing deal with the opposition. Mugabe's decision to swear in Joyce Mujuru and Joseph Msika came two days after state media announced that he would award the most important cabinet posts to his own party. Opposition leader Morgan Tsvangirai has already threatened to pull out of the power-sharing deal, saying Mugabe had violated the spirit of the pact meant to forge a unity government to end months of political unrest. "Whatever appointments or acts that do not address the woes of the country are meaningless," said Nelson Chamisa, spokesman for Tsvangirai's Movement for Democratic Change (MDC). South Africa's former president Thabo Mbeki was expected in Harare later Monday to meet with negotiators from the rival parties to try to salvage the deal, which he brokered four weeks ago. "He will meet with them starting from today, separately and jointly," Mbeki's spokesman Mukoni Ratshitanga told AFP. Both Mujuru and Msika have served as vice presidents for years, and their posts were not among the disputed cabinet portfolios. But Mugabe's decision to bring them to office without consulting the MDC cast a pall over Mbeki's latest mission before he even arrived. Mugabe's moves to tighten his grip on the cabinet would ensure his continued control over the military, police, and other security agencies. Under the power-sharing deal, 84-year-old Mugabe would remain as president while Tsvangirai would take the new post of prime minister. Their two parties were supposed to split the cabinet posts along with a small MDC splinter group. But Mugabe has left the MDC holding 13 mostly minor posts, while the MDC faction led by Arthur Mutambara would receive three. European Union foreign ministers meeting in Luxembourg slammed, in a joint statement, "the unilateral decision to form a new government which has not been agreed by all parties." They said they were "ready to consider additional measures" if the power-sharing deal remains blocked, referring to possible new sanctions against Mugabe and his associates. British Foreign Secretary David Miliband condemned Mugabe's "attempted power grab." "I think it is very important that a European signal goes out that we will have no part, and play no part in supporting a power grab by the Mugabe regime," Miliband told reporters as he arrived for the talks. The MDC argues that Mugabe's arrangement violates the spirit of the power-sharing deal, after the party won control of parliament in legislative elections earlier this year. Tsvangirai also defeated Mugabe in a first round presidential vote in March, but pulled out of a June run-off because of violence against his supporters that the MDC says left at least 100 dead. The power-sharing deal had been praised as an historic breakthrough that could end the political unrest and rescue the country from economic ruin. The political deadlock has dimmed hopes for restoring Zimbabwe's economic fortunes, which have plummeted since 2000, when Mugabe began giving white-owned farms to blacks who often lacked training for commercial agriculture. Once a regional breadbasket, the United Nations estimates that more than five million people " nearly half the population " need emergency food aid this year. Inflation soared to 231 million percent in July, while 80 percent of the population is unemployed.