Ford Motor Co. urged the UK to maintain its trade agreement with the European Union, warning that a measure under consideration to override the deal may threaten further investments in the country.

“Investors invest in good faith and on the basis that the UK is reliable place to invest,” Tim Slatter, who chairs Ford’s UK business, said Tuesday on the sidelines of an industry conference in London. “Part of that is to have a secure trading relationship with its biggest trade partner.”

Ford last year announced plans to invest as much as £230 million ($282 million) in retooling a transmission plant in Halewood near Liverpool to build electric-vehicle components—an investment Slatter said is dependent upon a stable trading relationship with the EU.

UK lawmakers are considering a bill that would allow the country to unilaterally amend the post-Brexit settlement for Northern Ireland, risking a trade war with the EU. After years of uncertainty, the deal following the UK’s exit from the bloc allowed the auto industry to avoid tariffs in its biggest export market, even as it added paperwork and lengthy delays.