Veterans of the country's liberation war have branded former Finance Minister Simba Makoni, a senior member of ZANU-PF, a traitor after he entered the race on Tuesday, in the first major challenge to Mugabe from within the ruling party in 20 years.

Makoni will run as an independent and, by standing against Mugabe, faced automatic expulsion under party rules.

"He has expelled himself from the party, he was not expelled by anyone but himself. That is the position according to the rules of the party. So yes, indeed, he is expelled from the party," ZANU-PF's secretary for legal affairs, Emmerson Mnangagwa, told Reuters.

Makoni had been expected to register for the poll on Friday but Zimbabwe authorities postponed the nomination date to February 15 after some politicians won a court order to delay the process.

On Wednesday, Zimbabwe's government-controlled media branded Makoni a British and American-sponsored puppet seeking to split ZANU-PF and oust Mugabe.

Joseph Chinotimba, deputy leader of the war veterans, was quoted as saying that Makoni was a political turncoat who would suffer a humiliating defeat in the March 29 general election.

"We are now going to campaign vigorously for President Mugabe. I feel sorry for Makoni, he has lost the political plot," Chinotimba told the Herald newspaper.

"From today to the nomination date we will have finished with them. Traitors should know that ZANU-PF has a history of dealing harshly with their kind."

ANCHOR OF CAMPAIGNS

Chinotimba said Mugabe's war veteran supporters -- the anchor of Mugabe's election campaigns since 2000 -- would not allow Makoni and his supporters to enter the party's offices.

"We are calling on all war veterans to take control of the party," he said.

War veterans, who fought in the 1970s conflict, along with members of ZANU-PF, have turned violent in the past in support of Mugabe. There are 30,000 war veterans in Zimbabwe.

Political analysts say Makoni is popular with the business community and urban voters disenchanted with Mugabe and the main opposition Movement for Democratic Change (MDC), but doubt he has the muscle to defeat the veteran Zimbabwean leader.

Zimbabwe's privately owned media have reported that Makoni is backed by a faction led by a retired army general and member of the ruling ZANU-PF party's top decision-making body, Solomon Mujuru. Mujuru is married to Vice-President Joyce Mujuru.

Makoni said he had consulted party members and activists throughout Zimbabwe before deciding to run. Despite economic turmoil, 83-year-old Mugabe is expected to defeat the divided opposition, although it is not yet clear how much support Makoni will receive.

Analysts say shortages of food, foreign currency and fuel, and the world's highest inflation rate -- officially pegged at 26,000 percent -- are the biggest challenge to Mugabe's rule.

But the opposition has failed to capitalise on Mugabe's failure to ease the crisis and it remains to be seen if daily hardships will push Zimbabweans to support Makoni.