* Official documents set out "no-deal" risks
* Minister says document is "worst-case" plan
* Report says UK will face fuel, food, drug shortages
* 85% of lorries "may not be ready for French customs"
* "Protests could break out across the UK" (Adds Merkel, fresh Gove comment)
By Kate Holton and William James
LONDON, Aug 18 (Reuters) - Britain will face shortages of fuel, food and medicine if it leaves the European Union without a transition deal, according to leaked official documents reported by the Sunday Times whose interpretation was immediately contested by ministers.
Setting out a vision of jammed ports, public protests and widespread disruption, the paper said the forecasts compiled by the Cabinet Office set out the most likely aftershocks of a no-deal Brexit rather than the worst-case scenarios.
But Michael Gove, the minister in charge of coordinating "no-deal" preparations, challenged that interpretation, saying the documents did set out a worst-case scenario and that planning had been accelerated in the last three weeks.
The Times said up to 85% of lorries using the main Channel crossings may not be ready for French customs, meaning disruption at ports would potentially last up to three months before the flow of traffic improved.
The government also believes a hard border between the British province of Northern Ireland and the Republic of Ireland, an EU member, will be likely as plans to avoid widespread checks will prove unsustainable, the Times said.
"Compiled this month by the Cabinet Office under the codename Operation Yellowhammer, the dossier offers a rare glimpse into the covert planning being carried out by the government to avert a catastrophic collapse in the nation's infrastructure," the Times reported.
Prime Minister Boris Johnson's office said it did not comment on leaked documents. But Gove said it was an old document that did not reflect current preparedness.
"It is the case, as everyone knows, that if we do have a no-deal exit there will inevitably be some disruption, some bumps in the road. That's why we want a deal," Gove told reporters.
"But it is also the case that the UK government is far more prepared now than it was in the past, and it's also important for people to recognise that what's being described in these documents... is emphatically a worst-case scenario," Gove added.
A government source blamed the leak on an unnamed former minister who wanted to influence negotiations with the EU.
"This document is from when ministers were blocking what needed to be done to get ready to leave and the funds were not available," said the source, who declined to be named. "It has been deliberately leaked by a former minister in an attempt to influence discussions with EU leaders."
NO TURNING BACK
The United Kingdom is heading towards a constitutional crisis and a showdown with the EU as Johnson has repeatedly vowed to leave the bloc on Oct. 31 without a deal unless it agrees to renegotiate the Brexit divorce.
Yet after more than three years of Brexit dominating EU affairs, the bloc has repeatedly refused to reopen the Withdrawal Agreement.
Brexit minister Stephen Barclay said on Twitter he had signed a piece of legislation which set in stone the repeal of the 1972 European Communities act - the laws which made Britain a member of the organisation now known as the EU.
Though his move was largely procedural, in line with previously approved laws, Barclay said in a statement: "This is a clear signal to the people of this country that there is no turning back (from Brexit)."
A group of more than 100 lawmakers wrote to Johnson calling for an emergency recall of parliament to discuss the situation.
"We face a national emergency, and parliament must now be recalled in August and sit permanently until October 31 so that the voices of the people can be heard, and that there can be proper scrutiny of your government," the letter said.
Johnson will this week tell French President Emmanuel Macron and German Chancellor Angela Merkel that the Westminster parliament cannot stop Brexit and a new deal must be agreed if Britain is to avoid leaving the EU without one.
Merkel said during a panel discussion at the Chancellery: "We are prepared for any outcome, we can say that, even if we do not get an agreement. But at all events I will make an effort to find solutions - up until the last day of negotiations."
Johnson is coming under pressure from politicians across the political spectrum to prevent a disorderly departure, with opposition leader Jeremy Corbyn vowing to bring down Johnson's government to delay Brexit.
It is, however, unclear if lawmakers have the unity or power to use the British parliament to prevent a no-deal departure, likely to be the UK's most significant foreign policy move since World War Two. (Editing by Gareth Jones and David Holmes)