Zimbabwe's Constitutional Court dismissed a case against President Robert Mugabe on Wednesday lodged by an activist who accused the aging leader of violating the southern African country's supreme law during protests last year.

The case was the first time a private citizen has asked the court to decide whether actions by 92-year-old Mugabe, the world's oldest leader, violated the constitution.

Mugabe, who has ruled the former British colony since independence in 1980, was last year confronted by the biggest anti-government protests in a decade. Security forces responded with teargas and water canon.

Political activist Promise Mkwananzi, whose #Tajamuka group helped organize the demonstrations, said in his application that Mugabe's response and speeches in the protests' aftermath "undermined national security and threatened citizens."

At a meeting with war veterans after one of the protests, Mugabe said his ruling ZANU-PF punished defectors during the liberation war by keeping them "underground like rats, in bunkers" - something he threatened to do to protest leaders.

Mkwananzi said Mugabe also claimed partisan control of the police and army, which is against the constitution.

But the nine-member Constitutional Court bench dismissed the case, saying Mkwananzi did not follow proper procedure in making his application. His lawyer consented to the decision.

"We are going to re-apply within 30 days in terms of the constitution, correcting those technicalities. We are not giving up," Mkwananzi told reporters after the 20-minute hearing.

"The court application is not the only route that we as #Tajamuka shall be taking. It is part and parcel of a multi-thronged strategy in pressuring this government to comply with the constitution and be accountable to the people," he said.

Attorney General Prince Machaya, who was representing the government, made no comment to the court other than to say the case should be dismissed.

Under Zimbabwe's laws, if the top court finds that a sitting president has violated the constitution, it can order parliament to start an investigation that could lead to impeachment.

Mugabe has been endorsed as ZANU-PF's candidate for presidential elections due in 2018.