Australian shares ended flat with a slight negative bias on Monday, as Beijing and Washington accused each other of violating recent trade agreements.

The S&P/ASX 200 Index was little changed to close at 8,414.10.

The US on Friday accused China of stalling critical mineral exports, while Beijing claims a trade deal breach and vows countermeasures, dimming hopes for a Trump-led leadership call.

"We continue to be in an investment environment punctuated by escalating and de-escalating tariff and related pressures," said David Chao, global market strategist at Invesco Asset Management in Singapore. "Markets are likely to respond in kind to these changing tariff winds."

On the domestic front, National Australia Bank (ASX:NAB) expects Australian first-quarter gross domestic product to rise 0.5% quarter on quarter and 1.7% year on year, broadly in line with the Reserve Bank of Australia's monetary policy statement for May.

Westpac Banking (ASX:WBC, NZE:WBC) expects Australia's first-quarter gross domestic product to rise 0.4% quarter on quarter and 1.5% year on year due to lower public spending.

In company news, Brickworks (ASX:BKW) and Washington H. Soul Pattinson (ASX:SOL) executed a binding combination deed to create an Australian Securities Exchange-listed company with a market capitalization of AU$14 billion. Shares of Brickworks rose 28% at market close and earlier hit an all-time high.

Coles Group (ASX:COL) will reduce prices on over 300 winter products, including meat, dairy, wines, pantry items, and snacks, effective Wednesday, for the next 12 weeks. Share of the company rose past 1% at market close.

Opthea (ASX:OPT) said there remains material uncertainty as to its ability to continue as a "going concern" as it continues to be in active negotiations with its development funding agreement investors.