German Economy Minister Peter Altmaier called on Monday for European states to close ranks in the trade dispute with the United States, following a dramatic end to the Group of Seven (G7) summit at the weekend.

A war of words broke out between the US and its traditional allies at the summit in Canada on Saturday, where trade proved a major stumbling block.

President Donald Trump attacked the summit host, Justin Trudeau, calling him ‘dishonest’ in a tweet that also announced the withdrawal of US support for a joint G7 communique, after the Canadian prime minister had vowed retaliation for US tariffs.

‘It's important that Europeans act in unity,’ Altmaier told German radio broadcaster Deutschlandfunk. Doing so would keep a ‘win-win’ situation possible, Altmaier said, though he added that no immediate agreement in the dispute over tariffs was in sight.

 German Chancellor Angela Merkel threatened Trump with retaliation in an unusually frank appearance on German broadcaster ARD late Sunday.

‘We won't let ourselves be pushed around time and time again,’ Merkel said, referring to Trump's decision to impose import duties on steel and aluminium of 25 and 10 per cent respectively.