LONDON (Reuters) – British online supermarket Ocado has denied robots were moving around its flagship complex at Andover in southern England when firefighters tackled a fire last week that wiped 1 billion pounds ($1.3 billion) off the group’s stock market value.

A report in The Times newspaper on Saturday quoted an unnamed firefighter as saying robots were still moving on a grid when they entered the complex, hampering their efforts to put out the blaze.

However, Ocado said in a statement: “The warehouse robots were immobilised by a safety system as soon as the fire alarm was activated.”

The fire at Ocado’s highly automated warehouse, designed to have hundreds of robots speeding along at four metres per second on giant steel and aluminium grids, started in the early hours of Tuesday but was not fully extinguished until Friday.

The cause of the blaze, during which the complex was largely destroyed, has not yet been established.

Hampshire Fire and Rescue Service (HFRS) also said it did not recognise the firefighter’s quote. “There will be a full and thorough investigation into the fire working with the owners to determine the cause and see if any lessons could be learned for the future,” said HFRS Deputy Chief Fire Officer Andy Bowers.

The Andover complex had been providing about 10 percent of Ocado’s capacity in Britain, using robotic technology the company is selling to grocery retailers around the world.

Shares in Ocado rallied 3.5 percent on Friday, having lost more than a billion pounds ($1.3 billion) in market value over the previous two days.

The losses reflected Ocado’s warning that the fire will dent its sales growth coupled with investor concerns that the blaze might have implications for the viability and cost of the technology it has sold and wants to sell.

The head of Britain’s firefighters union has called for a review of safety planning for automated machinery in the wake of the blaze.

“Fire safety planning … has not kept up to date with emerging landscapes, such as robotic warehouses,” said Matt Wrack, general secretary of the Fire Brigades Union.

“Since national fire service structures were scrapped in 2004, there has been virtually no mechanism for researching and preparing for emerging risks, such as those posed by technology,” Wrack said.

Ocado has said it would boost capacity at its other major UK sites to meet orders previously served by Andover. It is also considering other options such as a temporary site.

($1 = 0.7727 pounds)