A mercy-dash into Christchurch's earthquake cordon has averted a nationwide Guinness shortage on St Patrick's Day.

Lion Nathan staff were allowed into the damaged Canterbury Brewery in Christchurch's St Asaph St to rescue 1200 kegs of the famous Irish stout just in time for the national celebration of all things Irish tomorrow.

The lack of access to the brewery  which supplies the whole country with its Guinness - has meant pubs nationwide have experienced shortages and are ''on allocation'', meaning they can only order as much as they did last year.

Emergency stocks have also been flown in from Australia,  though Lion Nathan communications manager Renee White said this was only to ensure supply after the event.

The 1200 kegs rescued from the brewery were enough to supply the country for the day, she said.

Several Auckland publicans were doubtful they could get enough stock and had been stockpiling in the lead-up to make sure of supplies.

Father Ted's Original Irish Bar manager Colin Fitzsimons said he had not been selling Guinness because ''I wanted to save it for Paddy's Day''.

O'Hagan's manager Sharon Murray said they too had experienced a shortage in the run-up.

''We didn't know if we could have it [St Patrick's day],'' she said.

Ms Murray said she thought her kegs had come from Australia and they had arrived just in the nick of time.

 Ms White said Lion Nathan was footing the extra cost of importing kegs and the price of Guinness had not changed. 

- © Fairfax NZ News