HARARE  - Zimbabwe President Robert Mugabe said on Monday his country "was not for sale" and "will never be a colony again", while warning the opposition not to be "used by enemies." "Let's not hand over the country to the enemy," Mugabe said in a national address for Heroes' Day and ahead of a new round of power-sharing talks with his political rivals. "If you are on the enemy's side or you are being used by enemies, stop it ... It cannot just be unity in vain " a hollow unity," the 84-year-old leader said, addressing the audience in both Shona and English. "It must be unity guided by basic principles. Principles that will solidify us, strengthen us," he added in his address. He added in the address in honour of those who died in the guerrilla war that led to the country's independence: "Zimbabwe is not for sale and Zimbabwe will never be a colony again." Mugabe has often sought to portray opposition Movement for Democratic Change leader Morgan Tsvangirai as a stooge of former colonial power Britain, though his rhetoric has cooled in recent weeks with the two sides engaged in talks. He said "when somebody makes you turn against each other, you don't say we are no longer family members." Mugabe, himself a hero of the independence struggle, also declared "we will die for our legacy." "Fighting in self-defence is not a sin. So we fight to protect our legacy." The country's political rivals held marathon power-sharing talks that broke up in the early hours of Monday in a bid to end a crisis that intensified after Mugabe's widely condemned re-election in June. The talks have been mediated by South African President Thabo Mbeki, who remained in Zimbabwe on Monday. Mugabe "congratulated all the parties to the negotiations for exhibiting this sense of collective and shared responsibility," while thanking Mbeki, calling him "a very patient man." "We spent all night yesterday in discussions and some of the things that were holding back, at times I nearly raised my fist, but he remained cool." Mbeki held meetings beginning on Sunday morning with Mugabe, Tsvangirai and Arthur Mutambara, the leader of a smaller opposition faction. The talks were to resume later Monday after Heroes' Day commemorations.