According to sources, Biti tried to steer the budget and amendments to the Exchange Control Act through both Houses of Parliament, but was stopped in his tracks by the Senate on Friday after Mugabe was warned of the "political chicanery".
Biti, who is also secretary general for the MDC-T, struck a deal with Mujuru, also Mugabe’s deputy in Zanu-PF, to pass the budget through the National Assembly on Wednesday.
Mujuru and Biti were involved in intense negotiations in which they threatened to dismiss defiant MPs to ensure the budget was passed.
MPs were also promised new cars and to have their loans written off if they voted for the budget in the House of Assembly.
However, the budget ran into a stonewall in Senate on Friday after Zanu-PF Senators refused to vote for it following instructions from Mugabe’s aides, who warned that Biti wanted to emasculate the president under the guise of a budget process and legislative amendments.
Biti wanted to amend a chapter of the Exchange Control Act to remove Mugabe’s regulatory powers which deal with exchange control issues, including regulations on gold, currency, securities and exchange transactions.
The chapter also deals with the control of imports and exports from Zimbabwe, transfer or settlement of property, payments and transactions relating to debts.
A senior official in Mugabe’s office, who spoke to the Sunday Times, said the president was "shocked" after discovering that Biti has usurped his "sovereign powers conferred to him by the Exchange Control Act".
"The president was really shocked to see that the minister intended to usurp his powers under the guise of a budget process. What made the president even more angry was that vice-president Mujuru was collaborating with Biti on the issue," the official said.
"It’s a scandal and someone will have a lot of explaining to do. They can’t get away with it. They are trying to play power politics through the budget process."
Another Mugabe aide said the president’s advisors had detected "Biti’s Machiavellian" manoeuvres and warned the president.
"We realised that Biti’s proposed amendments to the Exchange Control Act would have serious implications on how exchange controls will be administered in this country. After a careful analysis of the amendments we discovered a sinister plot: that there was a plan to strip the president of his powers and weaken his position," Mugabe’s aide said.
Efforts to get comment from Biti, Mujuru and Mugabe’s spokesman George Charamba were unsuccessful. The situation is likely to deteriorate next week when the Budget is taken back to the House of Assembly where it could be passed again and sent directly to Mugabe who may or may not sign it depending on whether Biti climbs down on his proposals.
Mugabe’s aides said Mujuru is likely to suffer a ‘serious backlash" for backing Biti on the Budget process which they viewed as a plot to seize crucial administrative power from Zimbabwe’s ruler.