LONDON — Britain is pressing for U.S. plane maker Boeing Co. to drop its trade challenge against Canadian rival Bombardier and seek a negotiated settlement to try to protect jobs in Northern Ireland, its business ministry said on Monday.

British Prime Minister Theresa May also raised the issue in a call earlier this month to U.S. President Donald Trump, after Boeing complained earlier this year that Bombardier was dumping passenger jets on the U.S. market.

Bombardier is Northern Ireland’s largest manufacturing employer and May’s governing Conservatives are dependent on the support of a small Northern Irish party for their majority in parliament.

“Ministers across government have engaged swiftly and extensively with Boeing, Bombardier, the U.S. and Canadian governments. Our priority is to encourage Boeing to drop its case and seek a negotiated settlement with Bombardier,” a government spokesman said in a statement.

“This is a commercial matter but the U.K. government is working tirelessly to safeguard Bombardier’s operations and its highly skilled workers in Belfast.”

In April, Boeing asked the Commerce Department to investigate alleged subsidies and unfair pricing for Bombardier’s CSeries airplane, accusing the Canadian company of having sold 75 of the planes to Delta Air Lines Inc last year at a price well below cost.

The allegations were denied by Bombardier and the challenge has strained ties with Canada.

“Boeing had to take action as subsidized competition has hurt us now and will continue to hurt us for years to come, and we could not stand by given this clear case of illegal dumping,” Boeing said in a statement early on Tuesday.

“We believe that global trade only works if everyone plays by the same rules of the road, and that’s a principle that ultimately creates the greatest value for Canada, the United Kingdom, the United States, and our aerospace industry.”