LONDON (Reuters) – A no-deal Brexit could cause up to six months of disruption at some ports, a British minister warned on Friday, vowing to prioritise pharmaceuticals as the UK develops contingency plans less than four months before it is due to leave the EU.

Members of parliament look set to vote down Prime Minister Theresa May’s Brexit deal next week, hurtling the world’s fifth-largest economy into even deeper uncertainty and leaving open a number of possible outcomes including a disorderly Brexit.

Health minister Matt Hancock wrote to drugs companies in August to ensure they had at least six weeks’ worth of medicines in Britain but on Friday he suggested any potential disruption could last longer.

Hancock identified southern English crossings at the ports of Dover and Folkestone as areas which could be particularly affected.

“Revised cross-government planning assumptions show that there will be significantly reduced access across the short straits, for up to six months. This is very much a worst-case scenario,” he said in a letter to healthcare providers on Friday.

Firms in many sectors have been buying warehousing space and stockpiling to ensure they can meet demand and keep manufacturing going in the event that the frictionless movement of goods to and from the continent is lost.

Britain is planning to use aeroplanes and fast-track trucks to ensure the continued supply of medicines if it leaves the European Union without a deal, Hancock said, and will give preference to medicines in the face of competing pressures.

“The government has also agreed that medicines and medical products will be prioritised on these alternative routes to ensure that the flow of all these products will continue unimpeded after 29 March 2019,” he wrote.