A strike starts today (Thurs) at a factory that supplies millions of bottles of wine to the UK - which could spark a ''substantial'' national shortage.

The pay dispute by 200 workers has broken out at Bristol's Encirc - a firm which makes three billion glass containers for leading global booze brands.

Encirc is one of the major alcohol bottle fillers - with a 40 per cent market share and bottling 18 of the top 20 wine brands in the UK.

The Unite members at the Avonmouth site work across different areas, including bottling and packaging red, white, rose and sparkling wine and distributing it from warehouses.

It supplies all the major supermarkets with wine - and there are fears shelves could be left empty of plonk.

Over 200 Unite members at the Encirc site in Avonmouth are planning to strike between today and July 5.

The company has said it will "mitigate any impact" the Encirc strike may have and remains "open to dialogue with the union in good faith."

But experts say the knock-on effect to wine availability in supermarkets is likely to be ''substantial''.

Members at the factory work across different areas, including bottling and packaging red, white, rose and sparkling wine and distributing it from warehouses.

According to Unite, Encirc is a "very profitable company" with a turnover of over £600M supplying all the big supermarkets with bottles, box and bags of wine. "

Unite says the firm has only offered its workers a 3.2 per cent pay rise without negotiating with Unite and has now repeatedly stated from now on it will only give pay rises tied to inflation.

Unite says it effectively means removing Unite's collective bargaining rights, as any pay increases will be set by Encirc without negotiations before being imposed on workers. Previously, the union had been able to negotiate with management on pay.

Unite general secretary Sharon Graham said: "Encirc's meanness to its workers is all about greed and not need. This is a very lucrative company that can fully afford to pay its workers properly but it is choosing not to."

"Unite will not stand idly by and allow Encric to steal our members hard won rights. Encirc workers deserve better and they have Unite's full support throughout this dispute."

Strikes will take place between June 19 and 5 July - with workers in different parts of the business taking strike action on different dates and times according to production schedules to have the biggest impact.

There will also be a 12 week overtime ban as part of the action.

Unite regional officer John Sweeney said: "There is no doubt that this action will hit supermarket shelves. While shortages may be frustrating for customers looking to enjoy a bottle of wine this summer, the situation is entirely of Encirc's own making."

"Management has constantly refused to engage meaningfully. Encirc needs to return to the negotiating table with a vastly improved offer."