Updated

The Irish border is once again a stumbling block in Brexit talks, with anti-EU politicians accusing rivals of using it to keep Britain from fully leaving the European Union.

Britain and the EU agreed in December that the all-but-invisible border between Ireland and Northern Ireland would remain open after Brexit in 2019, but they left it unclear how that would happen in practice.

On Wednesday the EU will publish a 120-page draft agreement, translating the December commitments into legal language.

Pro-Brexit politicians in Britain are balking at reports that the EU will say that, if other solutions are not found, Northern Ireland should continue to adhere to EU rules.

Foreign Secretary Boris Johnson accused Brexit opponents of using the border to tie Britain's hands "so we cannot really leave the EU."