LONDON (AP) — Lawmakers scrutinizing Britain's exit from the European Union said Thursday that progress in trade talks with the bloc is "highly unsatisfactory," and that the country may have to stay in the tariff-free EU customs union for years after Brexit.

The Exiting the European Union Committee said in a report that time is running out to set up new trade arrangements, and staying in the customs union may be "the only viable plan."

Britain is due to leave the EU in March 2019, followed by a 20-month transition period. The committee said it's unlikely new customs procedures, which have yet to be agreed on, will be in place by the time the transition ends in December 2020.

"It is highly unsatisfactory that nearly two years after the referendum, ministers have yet to agree, and set out in detail, what kind of trading and customs arrangements they wish to seek" with the EU, the report said.

Committee chairman Hilary Benn, an opposition Labour Party lawmaker, said Britain will probably have to remain in a customs union "until alternative arrangements can be put in place."

Benn said that, 23 months after the June 2016 referendum, "we still don't know what the U.K.'s future relationship with the EU will be on trade, services, security, defense, consumer safety, data, broadcasting rights and many other things."