Britain says hopes US will honour G7 commitments on trade

"The communique was agreed by all the parties who attended the G7 and we fully intend to honour it. We would hope that the US will similarly honour the commitments that they have made," he said.

The summit in Canada ended in farce and a renewed threat of trade war on Saturday after Trump rejected an attempt to write a consensus statement and bitterly insulted the Canadian host.

The joint communique that was thrashed out over two days of negotiations vowed that members would reform multilateral oversight of commerce through the World Trade Organization (WTO) and seek to cut tariffs.

"We commit to modernize the WTO to make it more fair as soon as possible. We strive to reduce tariff barriers, non-tariff barriers and subsidies," it said, reflecting the typical language of decades of G7 statements.

Trump had already said he would not hesitate to shut countries out of the US market if they retaliate to steep tariffs he has imposed on steel and aluminium imports.

The joint communique was published online before Trump tweeted his disapproval after comments made by Canadian Prime Minister Justin Trudeau.

"Based on Justin's false statements at his news conference, and the fact that Canada is charging massive Tariffs to our US farmers, workers and companies, I have instructed our US Reps not to endorse the Communique as we look at Tariffs on automobiles flooding the US Market!" Trump tweeted.

"PM Justin Trudeau of Canada acted so meek and mild during our @G7 meetings only to give a news conference after I left saying that, 'US Tariffs were kind of insulting' and he 'will not be pushed around.' Very dishonest & weak." Trudeau had told reporters that Trump's decision to invoke national security to justify US tariffs on imports of steel and aluminium was "insulting" to Canadian veterans who had stood by their US allies in conflicts dating back to World War I.

"Canadians are polite and reasonable but we will also not be pushed around," he said.