WASHINGTON/OTTAWA (Reuters) - The U.S.-Canada border will close to nonessential traffic, U.S. President Donald Trump tweeted on Wednesday, saying details on the move would be announced later but that it would not affect trade between the two countries.

“We will be, by mutual consent, temporarily closing our Northern Border with Canada to non-essential traffic. Trade will not be affected,” Trump wrote.

A Canadian source had earlier said the two nations were working on a deal to close the frontier to non-essential travel as part of the fight against a coronavirus outbreak.

Under the terms of the proposed deal, the flow of goods between the two nations - which share one of the world’s largest bilateral trading relationships - would continue.

The U.S. and Canadian economies are highly integrated and a strict ban on border crossing would cause major problems for the auto sector as well as the transportation of food and medicines.

Ottawa closed the borders to most foreign nationals on Monday but excluded U.S. citizens.

This upset the Pacific province of British Columbia - directly to the north of Washington state, one of the worst-hit spots in the United States - which pushed for American visitors to be banned.