The drinks giant plans to close its Johnnie Walker bottling plant in Kilmarnock and the Port Dundas grain distillery in Glasgow under proposals unveiled in June and confirmed last month.

The plans have been criticised by trade unions and politicians north of the border.

Addressing the company’s annual shareholder meeting in London, Walsh said: “Our decision around Scotland has been made. It is now about how we apply that decision.”

He went on: “I would be misleading... if I suggested we can revisit the decision.”

Walsh had what one company insider described as a “frank” 20-minute meeting with five worker representatives before the meeting, but refused to budge on the closure plans.

There were also protests outside the company’s operations in Kilmarnock and Glasgow.

Alex Howie, shop steward for the Unite union at Kilmarnock, told The Herald: “They are hearing us but they are not heeding us.”

Bill Anderson, Unite shop steward at Port Dundas, said: “They came up with a proposal on day one and haven’t changed their attitude since.”

He added: “They are destroying communities and getting rid of quality jobs and it is a crying shame for the generation coming in.”

Walsh said he is “empathetic” towards affected workers, but denied the company is adding to joblessness in areas with high levels of unemployment.

“I am aware that in the west of Scotland there are certain unemployment issues that may be perceived to be more acute than elsewhere.

“If you look at the absolute levels of unemployment there, they are not massively different.

“That said, if employees from Kilmarnock wish to take the opportunity to move to the jobs being created in another facility we will work with them to facilitate that transfer.”

Under Diageo’s plans, 400 jobs will be created at its packaging plant in Leven, Fife.

Walsh, who faced calls from some individual shareholders to reconsider the move, said Diageo needed to compete with low-cost rivals in emerging markets in Latin America, Asia, and Russia. The world’s largest drinks company is facing a particular struggle in China, where it is currently the market number two and locally made rice wine predominates.

Walsh said of the closure plan: “It is a decision we have to take in order to protect the future of Scotch whisky and also this firm.”

He added: “Our job is to make sure Scottish whisky can be actively marketed around the world and can effectively compete with products it stands up against, (such as) Chinese white spirit in China, so we must have the most efficient facility.

“Therefore we have reconfigured our footprint in Scotland.

“I do realise that is not very comfortable for those people affected, but we will do our utmost to make sure the transition goes as smoothly as possible.”

He said alternative proposals presented to him, including from a Scottish Government-backed taskforce, “didn’t achieve anything like our objectives around productivity and efficiency”.

He added the company might invest less than £100m planned for the facility in Fife if it can make cost savings.

Walsh dismissed fears that the release of convicted Lockerbie bomber Abdelbaset Ali Mohmed al Megrahi from Greenock jail had hit whisky sales in the United States, saying that Diageo’s lobbying of US politicians had reduced the impact.

“We found very quickly the heat around the issue subsided and we have not seen any direct impact on our products.”

Diageo’s shares closed down 20p or 2.1% yesterday, at 956p, after the company told investors that sales are 6% down on last year. Analysts had expected a drop of just over 2%.

Walsh said: “The year has started as we thought it would and we reiterate our guidance for low, single-digit organic growth in operating profit in fiscal 2010.”