Harare - Zimbabwe's vice president Emmerson Mnangagwa on Thursday fought back against allegations by his co-deputy that he lied about being poisoned, in a row that displays the growing political in-fighting ahead of next year's election. Mnangagwa has been accused by fellow vice president Phelekezela Mphoko of undermining President Robert Mugabe by claiming to have been poisoned during a ruling Zanu-PF rally in August."I never said I was poisoned in Gwanda, but that I fell ill," he said accusing Mphoko of "subjective falsehoods and mischievous perceptions"."My commitment to national unity, peace and stability is undoubted and unquestionable," he added, dismissing Mphoko's claim that he was attempting to undermine Mugabe's authority."I have an impeccable history of unflinching loyalty to the party, and his excellency the president, comrade Robert Gabriel Mugabe and have never acted in a manner that undermines his authority or the stability of Zimbabwe."Mnangagwa, 75 is one of the favourites to succeed Mugabe, while Mphoko is seen as having no plans to run for the leadership.Mnangagwa was flown to South Africa for emergency treatment after falling ill at the Zanu-PF party rally in the southern town of Gwanda on August 12."The doctors who attended to me ruled out food poisoning, but confirmed that indeed poisoning had occurred and that investigations were still in progress," said Mnangagwa.Some supporters claimed he had been given poisoned ice cream in an attempt to kill him.Mugabe, 93, has maintained strict discipline over his government for decades, but the public dispute has exposed growing in-fighting over who will eventually succeed him.