An injunction from the National Court bars the protesting students from barricading and locking classrooms, as well as boycotting classes, officials said.

For several weeks, Papua New Guinea has been rocked by demonstrations against Prime Minister Peter O'Neill, with students accusing him of corruption and mismanagement. Thousands of students across the country have been boycotting their lessons.

Education Minister Malakai Tabar praised the court's decision late Wednesday.

"The overwhelming majority of students simply want to go to class, sit their exams and proceed to the next semester," he said.

"Hard working students have been held hostage by the people with political agendas and that has now been brought to an end by court order," he added.

Tabar blamed the recent violence on "thuggery" and the opportunists among the government critics.

"We all know that the real ringleaders behind the incident are not students, and now it will be hard for them to hide amongst the student body," he said.

Shooting from patrol cars

The court decision follows a day of violence that saw police open fire at students in the capital, Port Moresby. Ahead of the scuffle, the students were gathered to march towards the parliament as the deputies considered a vote of no-confidence against O'Neill.

Journalism student Staycey Yalo said the group encountered a police block. The officers demanded the protesters to hand over the student president, which the students refused to do, prompting an argument.

"They threw tear gas and amidst the smoke, they started shooting directly at the students," Yalo told the AP news agency by telephone. "That's when we all ran."

Police started chasing after the protesters and shooting at them from their cars, Yalo said.

The government offered a different version of events, with O'Neill saying he was told a small group of students became violent, threw rocks at police and "provoked a response that came in the form of tear gas and warning shots."

Critical wounds

Amnesty International cited information that 38 people were hurt during the shooting, and that four of them had critical injuries. The local "Post Courier" newspaper reported that one person was shot in the head and another one in the chest.

"The shooting of students peacefully protesting is reminiscent of the worst excesses of repressive regimes in the region," said Rafendi Djamin, Amnesty International's director for South East Asia and the Pacific.

Police Commissioner Gari Baki said an investigation was underway, but warned that security forces would be out in force to ensure order on Thursday.

"Police in the city and around the country will come down hard on any opportunists who want to cause trouble," he said.