"The scene outside Parliament is very tense. There are dozens of police cars and army vehicles," the witness said, adding that a nearby hotel was in lockdown and the protesters were blocking traffic. The group later marched down the street towards a nearby stadium.
The chief executive of Papua New Guinea's Apec Secretariat Chris Hawkins told Australian broadcaster ABC that the payment would "normally take a week to process at the end of a major event".
"The meeting ended two days ago and the security operation is now winding down," he said.
"The payment of individual allowances has already commenced and individual security force members should check with their banks as payments are made."
The Asia-Pacific Economic Co-operation (Apec) meeting was attended by New Zealand Prime Minister Jacinda Ardern, United States Vice-President Mike Pence, Chinese President Xi Jinping, Japan's Prime Minister Shinzo Abe and others.
Papua New Guinea, the poorest member of Apec, had rolled out the red carpet for visiting world leaders during the two-day conference and bought 40 Maseratis to ferry the dignitaries around.
Following the rampage, about 100 police and guards waited outside Parliament demanding to be addressed by the Government about their allowances, Kramer said.
"The situation here is quite tense," Kramer said from Parliament on social media.
"Numerous staff of Parliament were assaulted during this confrontation."
Working police later provided security for parliamentary staff in the building and patrolled surrounding streets.
Neither Prime Minister Peter O'Neill's office nor Police Chief Superintendent Dominic Kakas immediately responded to requests for comment.
Kramer also did not immediately respond to a request for comment.
Papua New Guinea is a largely undeveloped Pacific nation of more than 8 million mostly subsistence farmers with widespread poverty, corruption and lawlessness.
The annual Apec summit brought together representatives of 21 nations that account for 60 per cent of the world economy.
- Agencies
