The company produced 192,510 tonnes of copper and 70,120 ounces of gold in the September quarter, up 27% and 56% respectively from a year earlier.
The new Cobre Panama mine had contributed 56,221t of copper and 21,484oz of gold to the result, of which 19,438t and 7,914oz were deemed commercial.
The company had declared commercial production at the giant Panama mine on September 1 and Newall told an earnings conference call the operation was "very quickly establishing itself as a cornerstone asset".
"It's fair to say that it's a special moment in the evolution of First Quantum as our largest and likely our most complex project to date has entered commercial production," he said.
Elsewhere, Newall said the company was seeking clarification on Zambia's tax changes, with a proposed sales tax scrapped in the latest budget and adjustments flagged for the VAT system.
He reiterated the company was holding discussions regarding a potential sale of a minority stake in its Zambian copper assets but said there was no guarantee a transaction would result.
In Spain, he said the Las Cruces copper mine had "begun its recovery" from a January land slippage earlier this year.
In Western Australia, First Quantum was aiming to restart its Ravensthorpe nickel operation in the first quarter of 2020 and produce about 25,000t per year.
He said capex figures on the Ravensthorpe restart were still soft at this point.
"We can start-up in the existing pit, but there's only a couple of years left of resources in that pit," he said on the call.
"It's the move to the next pit that is where there is capital expenditure.
"And the largest component of that is an overland conveyor, including a bridge across a highway to the next ore body."
First Quantum reported a loss of US11c per share, down from earnings of 9c a year ago, and comparative earnings per share of 5c, compared with 19c in the previous corresponding period.
Sales revenue was $9 million higher at $987 million.
The company ended the quarter with $406 million of net unrestricted cash and cash equivalents.
Its share price gained 3.7% yesterday to close at C$11.64, capitalising First Quantum at $8 billion (US$6.1 billion).
It had peaked at $16.63 in April but fell as low as $7.835 in August.