The criticism comes less than a day after Prime Minister Malcolm Turnbull declared Australian border security “the best in the world”.
“For us, offshore asylum treatment has some problematic aspects, we have always said it, we have said it very openly,” said Grandi.
“The strong focus in Europe, Australia and North America has really been on safety and control.
“This is really just looking at the problem at the end of the process.
“We really need to look at the root causes of the problem and we need to address them.”
Despite opposition from presidential candidates Hillary Clinton and Donald Trump, Turnbull has once again urged the United States Congress to approve the Transpacific Partnership Trade Agreement.
The Australian ambassador to the United States, former treasurer Joe Hockey, led the lobbying effort in Washington DC.
“There is a fair degree, I would say only a fair degree of optimism that it will be ratified during the lame duck period,” Turnbull said.
Australia’s hopes now rest on congressional approval of the deal after the November election and before President Obama leaves the White House in January.
“It will be a lot harder to do later,” Turnbull said.
“This is a window of opportunity and I believe it will be in the long-term interest of America, as well as the rest of Asia Pacific, and particularly Australia, to ratify it.”