The Government has vowed to work to overturn “completely unjustified” tariffs slapped on plane maker Bombardier by the US, amid fears it could spark a trade war and threaten 4,100 jobs at plants in Northern Ireland.

Ministers hit out at the US commerce department’s decision yesterday to recommend tariffs as high as 219pc on imports of Canadian plane maker Bombardier’s C-series commercial jets.

The decision enraged UK unions who fear the move threatens jobs at Bombadier’s Belfast aircraft wing factories and demanded the Government safeguard the jobs.

Prime Minister Theresa May said she was "bitterly disappointed" by the ruling and would work to protect “vital jobs for Northern Ireland”.