Soldiers, police officers, and prison staff staged a lively but peaceful protest this morning, after noticing their pay had been docked without explanation.

But by this afternoon, pockets of unrest had spread through the capital Port Moresby, with video clips on social media showing crowds looting shops and stretched police scrambling to restore order.

“It’s unfortunate that the situation has turned out this way, so uncalled for,” police commissioner David Manning said.

“But we are doing all we can to control the situation in the city.”

Crowds tried to smash a chain on a tall security gate outside the prime minister’s office, video images showed, before eventually tearing it off its rails.

They then unsuccessfully tried setting fire to a guard post, before eventually torching a white police SUV parked outside the compound, an AFP correspondent on the scene said.

While security forces started the demonstrations, it was unclear if they were responsible for the ensuing turmoil.

The AFP correspondent based in Port Moresby said a mix of “police, soldiers, and civilians” appeared to be involved.

The government said the pay deductions were the result of an unintended glitch, and has promised to fix it promptly.

“I want to appreciate all of you today,” internal security minister Peter Tsiamalili said in conciliatory remarks to protesters before the trouble began.

“I just want to again reassure all our policemen and women that I am here to make sure that your welfare is addressed.”