HARARE, Zimbabwe (CNN) -- President Robert Mugabe reiterated militant warnings on Saturday as the deputy leader of Zimbabwe's main opposition party was brought to court on treason charges.

Appearing at a funeral for a war veteran in Harare, Mugabe issued a dire warning in an address broadcast over radio against the opposition Movement for Democratic Change (MDC).

"We shall never, never accept anything that smells of ... the MDC," Mugabe said. "These pathetic puppets taking over this country? Let's see. That is not going to happen."

A day earlier, Mugabe warned that veterans he commanded in his country's liberation war will take up arms again to prevent the opposition party from taking power.

Mugabe told supporters that MDC leader Morgan Tsvangirai would turn the country back over to white control if he won the runoff later this month.

The veterans he led in a successful effort against a government dominated by the white minority were not prepared to recognize a Tsvangirai victory, Mugabe said.

A presidential runoff election has been set for June 27 pitting long-time Mugabe against Tsvangirai. There have been numerous reports from the opposition and church groups about kidnappings, torture and other violence, including the deaths of opposition party members. They say the violence targets opponents of Mugabe and his Zanu-PF party.

Tsvangirai has been detained several times in the weeks leading up to the runoff election -- most recently on Saturday with the 11 others.

National police arrested the dozen MDC members at a roadblock near Shurungwi, according to a party spokesman.

Meanwhile, Zimbabwean police brought opposition party secretary-general Tendai Biti to Zimbabwe's High Court on Saturday after they received two court orders to do so, a journalist at the court said.

Biti briefly appeared before Justice Ben Hlatshwayo in the court, the journalist said. The secretary-general wore leg irons and appeared "dejected and dull," the reporter said. His attorney, Lewis Uriri, described him as "unnaturally" reserved.

Still, it was a court appearance Biti's lawyer had fought for and one that Zimbabwe's national police appeared reluctant to comply with.

Police had initially questioned the validity of a court order for Biti to appear, but they finally complied with a second order to bring him to court two hours later, the reporter said.

Biti was scheduled to appear at the Magistrate's court in Harare on Monday to formally face charges of treason and disseminating malicious falsehoods. National police said the case against Biti is tied to a document published by his party, the Movement for Democratic Change, before the March 29 presidential election.

After the court proceeding, Biti was returned to police custody. He was being held at Matapi Police Station, in Mbare, the oldest suburb of the capital city.

"Obviously, he was depressed because they are (holding) him for no reason, really," said George Sibotshiwe, spokesman for Movement for Democratic Change leader Morgan Tsvangirai.

Sibotshiwe, who was detained for three hours himself on Saturday with Tsvangirai and 10 other people, called the charges against Biti, "ridiculous."

However, he said, "We are happy with his appearance," and alleged that he was not being fed.

Uriri said the government will allow him access to Biti, saying that his understanding from the state is "that we can have unconditional access to him."

Biti said he did not have any complaints against police, the attorney said.

Police arrested Biti Thursday as he arrived in the Zimbabwean capital on a flight from South Africa. A warrant had been issued for his arrest on June 6, when he was abroad.

Though reports of violence have been common in Zimbabwe, there has been a significant uptick in attacks since the elections, which resulted in a bitter standoff.

All About Zimbabwe • Robert Mugabe • Morgan Tsvangirai