OIL giant Valero has expressed major concerns about plans for petrol tariffs in the event of a No Deal Brexit, following publication of leaked documents that suggested two oil refineries could be forced to close.

Valero Pembroke Refinery General Manager Ed Tomp spoke out after The Sunday Times published details of Operation Yellowhammer.

The documents warn that Britain will be hit with a three-month "meltdown" at its ports, a hard Irish border and shortages of food and medicine if it leaves without a deal.

It also states that Government plans to set petrol import tariffs at 0% could seriously damage the oil industry in the UK.

While fuel imports would not be subject to tariffs, exports would be, removing the level playing field.

Operation Yellowhammer stated: "This leads to big financial losses and the closure of two refineries (which are converted to import terminals) with about 2,000 direct job losses."

The Valero refinery employs around 500 people plus hundreds of contractors.

Mr Tomp said: “Over the last 12 months we have made preparations to ensure that Valero Pembroke Refinery continues to operate safely and reliably regardless of whether the UK leaves the European Union on October 31.

“However we are concerned that 0% import tariffs on petrol could create an unfair advantage for importers, resulting in a negative impact on all UK refineries.

“As such we have been working with UKPIA (United Kingdom Petroleum Industry Association) to ensure our concerns – and the potential impact of zero tariffs - are clearly communicated to the UK Government.”

Preseli Pembrokeshire MP Stephen Crabb said Valero Pembroke Refinery would be hit hard by such a situation.

The Conservative MP, said: "No one should underestimate the importance of Valero to the Pembrokeshire economy through the large number of high quality jobs it provides and its large capital spending each year.

"A No Deal Brexit risks undermining the strength of the whole UK oil refining sector because the Government intends to impose zero tariffs on fuel imports from the EU but UK exports would be hit by tariffs from the EU side so there will no longer be a level playing field.

"Overnight UK refiners would become uncompetitive against EU rivals. This would jeopardise Valero’s important trade with Ireland.

"Valero have shown through their investment that they want to be in Wales for the long term but a No Deal Brexit, on the terms that the Government proposes, creates an incredibly challenging environment for the company.

"Over the last year I have warned that a No Deal Brexit poses particular risks to British oil refineries and have raised these in Parliament and with Ministers directly. My concern about Valero was one of the biggest factors behind my decision to vote for the draft deal on three occasions.

"With the public mood in Pembrokeshire swinging more behind No Deal in recent months, it is important that there is an honest discussion about it.

"I hope Boris Johnson can get a better deal agreed in the autumn but, if not, I will continue to urge a rethink on the proposed No Deal tariffs so that a level playing field can be maintained for UK oil refineries."

Michael Gove - the Cabinet minister responsible for no-deal planning - insisted Yellowhammer represented a "worst-case scenario".