Peter O'Neill has not acceded to the demands of students at the University of PNG, who are calling on him to resign over a major fraud case he is implicated in.
Police fraud squad officers had secured an arrest warrant for Mr O'Neill over the matter two years ago, but his lawyers have launched a series of challenges which are yet to be finalised in court.
A spokesperson for the university's student representative council, Gerald Tulu Manu-Peni, said the students were pondering their next move, which could include a mass withdrawal from courses.
"Student leaders have agreed, when the ultimatum lapsed, they have consulted their provincial and regional groups and all have come to a resolution that we will continue on with the indefinite boycott for the coming week," said Mr Manu-Peni.
But despite the growing pressure on Mr O'Neill, he still retains the support of his government MPs.