"Goods are flowing effectively and in normal volumes between Great Britain and Northern Ireland ... There are teething problems .... but I can confirm ... that if there are problems that we believe are disproportionate then we will have no hesitation in invoking Article 16," he told parliament.

Article 16 of the Northern Irish protocol, which covers post-Brexit trade between Britain and Northern Ireland, details so-called safeguard measures, which allow either party to take unilateral measures if there is an unexpected negative effect arising from the agreement.

(Reporting by William James and Elizabeth Piper; Editing by Kate Holton)