Harare - Zimbabwe's veteran leader Robert Mugabe has used a two-hour television interview to ridicule his former deputy who launched a new political party this week to challenge his all-powerful ZANU-PF.
In his first public reaction to the opposition party set up by former vice president Joice Mujuru, Mugabe said: "They will live in the wilderness, where little ants and other biting insects are destined to live".
"Some think we are afraid of them. We are not."
Mujuru, who was sacked by Mugabe in 2014, officially unveiled the Zimbabwe People First party on Tuesday.
A former ZANU-PF stalwart and liberation war veteran, Mujuru served in all cabinets under Mugabe and was seen for many years as his favoured choice of successor.
But she was fired after a sustained campaign by the president's wife Grace, who accused her of fomenting party division and plotting to topple Mugabe, who turned 92 two weeks ago.
As speculation increases over his succession, Mugabe vowed he would not hesitate to expel disloyal party members.
"The party will always have negative elements. Those we feel are troublesome, we chuck them out," he said,
In his annual birthday interview screened by the state broadcaster ZBC on Thursday night, Mugabe ruled out naming a successor, saying he was nearing his goal of ruling until he is 100.
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"I want to reach 100 years so I have only eight strides to go,' he said.
"I did not go into the 2013 election for someone else to complete my term which ends in 2018."
He is expected to stand again for election in 2018, but jockeying over who will take over after him has intensified due to his advanced age and speculation about his health.
Mugabe has ruled since independence from Britain in 1980, overseeing a regime marked by vote-rigging, mass emigration, accusations of human rights abuses and economic decline.
He joked about another bout of rumours that he had died during his annual holidays to Asia.
"I still exercise to keep alive, to resurrect when people say I am dead. Every January I must prepare the necessary exercise to resurrect."
Mugabe also downplayed reports that he is preparing his wife, Grace, 50, to succeed him.
"Where has it ever happened that a wife becomes a successor?" asked Mugabe.
"I have no authority to appoint someone as president after me."