Justice Minister Patrick Chinamasa warned Botswana of dire consequences
Botswana has rejected claims by Zimbabwe it is involved in a plot to oust President Robert Mugabe.
Zimbabwe's justice minister told state media they have "compelling evidence" Botswana was hosting military training camps for opposition rebels.
He said Botswana was helping recruit youths to destabilise and bring about illegal regime change in Zimbabwe.
But Botswana said it was "nothing more than distorted or concocted evidence, none of which is supported by facts".
A statement from Botswana's ministry of foreign affairs said: "Zimbabwe has signally failed to produce any tangible, much less compelling, facts in support of its allegations."
The ministry said it had already rejected Zimbabwe's claim "in the strongest possible terms" in a response to the Southern African Development Community (Sadc), which says it is investigating the allegations.
Sadc secretary general Tomaz Salamao confirmed earlier his organisation was analysing documents and videos submitted to them by the Zimbabwean authorities.
Observers say it is the first time that such openly hostile relations have emerged among any of the 15 Sadc members.
Botswana's President Ian Khama is one of the few African leaders to have publicly criticised Mr Mugabe.
Mr Khama has called for new elections after Mr Mugabe and opposition Movement for Democratic Change (MDC) leader Morgan Tsvangirai reached deadlock in power-sharing negotiations.
Justice Minister Patrick Chinamasa told the state-owned Herald newspaper: "Botswana has availed its territory, material and logistical support to [the MDC] for the recruitment and military training of youths for the eventual destabilisation of the country with a view of effecting illegal regime change.
"We now have evidence that while [the MDC] were talking peace they have been preparing for war and insurgency, as well as soliciting the West to invade our country on the pretext of things like cholera."
He claimed the opposition was "bent on foisting war on the country and the region" and warned Botswana of dire consequences.
Opposition spokesman Nelson Chamisa dismissed the minister's claims saying: "When a leopard starts devouring its young ones, it starts by accusing that young one of smelling like a goat."
The UN Security Council is due to meet later in New York to receive a briefing - requested by European countries - from UN officials on Zimbabwe.
Analysts say it marks the 15-member body's re-engagement with Zimbabwe following July's veto of sanctions against Mr Mugabe and his allies by Russia and China.
A cholera epidemic that has killed nearly 1,000 people and infected more than 18,000 people, together with Zimbabwe's economic meltdown, have sparked new calls from Mr Mugabe's Western critics for the departure of the 84-year-old leader, who has ruled since independence in 1980.
Zimbabwe's government has blamed the cholera outbreak on Britain
The outbreak has been fuelled by the collapse of the country's health services, sanitation systems and water supply.
The justice minister's allegation comes a day after the US Ambassador to Zimbabwe, James McGee, accused Mr Mugabe of "criminal negligence" and warned Zimbabwe was becoming a failed state.
Writing in South Africa's Sunday Times newspaper, Mr McGee said: "What is the Mugabe regime doing? It is buying hundreds of cars so that every minister and governor can have multiple vehicles. It is buying plasma televisions for judges.
"Instead of spending scarce resources on water purification chemicals that might stop the cholera epidemic, they are manipulating currency to make a personal profit."
Mr Mugabe last week sparked uproar by claiming the cholera outbreak was over in Zimbabwe, while Information Minister Sikhanyiso Ndlovu said the outbreak was the result of biological warfare launched by former colonial power Britain against Zimbabwe.
Meanwhile, police have reportedly arrested a Zimbabwean journalist at his Harare home.
Accredited freelance reporter Andrisson Manyere was detained on Sunday, according to South African privately-owned newspaper The Star.
The reported detention follows a warning on Saturday by Mr Mugabe's spokesman of state action against journalists for "mis-reporting" on the cholera outbreak.
There has been growing concern in Zimbabwe about the number of human rights activists and MDC supporters who have been abducted since October. Some 18 are reportedly missing.